I am going to have a pinewood derby event for my employees and I did the pinewood derby’s when my kids were younger and nephews (got 1st in all races including the districts & overall, so to many to mention). I appreciate the video bc it’s been about 8yrs and I will have my staff watch your video to help identify cheating (I want all employees to have a fair shot). I will be allowing lighter wheels but that is it! Thanks again
Here's another idea to make it fair... bring them all together and only give them 2 hours to build cars... no testing... just build and then race. Fun and Fair!
no a lighter wheel by itself will not move a car faster while propelled by gravity...... but it will allow more weight you can use at the back of your car. which allows a higher center of gravity = more kinetic energy.
Basic physics says that the mass of the wheel is irrelevant when racing just wheels. it is all about mass distribution. The further the mass is from the axle the slower the it will roll. When you put wheels on a car it does make a difference though -- there you want the least mass rotating (more precisely, the least rotational kinetic energy and so the smallest rotational moment of inertia)
You said it a lot better than I did... or could! Wheels alone don't show the difference. If I had time, I could have demonstrated that with the weight of the car and gravitational pull, the lighter wheels rotate more quickly off the starting block.
@BS STW If you take a heavy wheel vs a light wheel, the heavy wheel will start rolling down the hill slower. A light wheel on a hill will start rolling more quickly because there is not as much mass (weight) to get moving down the hill. Once you get a heavy wheel rolling with all that weight, it will have more power and roll for longer distance; however, the pinewood track is not that long, so it is better to have a LIGHT wheel. (And put the extra weight into the body.)
@@thanethebrain The lighter wheels DO NOT rotate more quickly off the starting block they may rotate more slowly, if the lightening was achieved by hollowing out the rotating body but cannot be made faster by changing weight nor diameter. (nor width). th-cam.com/video/cB8GNQuyMPc/w-d-xo.html
My kids first year in scouts we just drew on the axels with a pencil and what a difference! We got a tube of graphite this year. Hopefully it helps even more.
The lighter wheel does not roll faster because it weighs less. It rolls faster because it has a lower moments of inertia. For example, if you took two cylinders made of the same material, one hollow and one solid, the solid cylinder, even though it can weigh significantly more, would roll faster because its mass is more evenly distributed throughout its shape. In this particular case, the lighter wheel rolls faster because its mass is more evenly distributed. What you do not want is for the mass to be concentrated at its circumference. Also, because there is a force applied to the wheel at the axle, the moment of inertia of the wheels becomes less relevant in the context of the greater mass of the entire car.
@@thanethebrain weight is irrelevant, it could weigh 6 lbs or 6 ounces, if the geometry is the same, it will roll at the same rate. The higher the percentage of mass at the center, the faster it will roll. The 'lightening" is simply removing edge material so that more of the total material is concentrated at the center. If two wheels weighed the exact same, one with spokes and as much weight as possible at the edge, and the other like a discuss with its weight concentrated at the center, the one with the weight at the center will roll faster, even though they weigh the exact same.
If its specifically does NOT state "you can't XXXXX " then YOU CAN... [Smokey Yunick] A lighter rotating mass will accelerate QUICKER= YES......but a pinewood track also has a long flat portion...where the car will decelerates per friction. Having a greater rotational mass will it decelerate SLOWER given the SAME friction. NOW...it is a balancing act between total weight-rotating MASS - friction loss.
The tests are in. There is more benefit to a lighter wheel on the pinewood track. If the track were 100 feet long, then perhaps more mass in the rotating wheel would be better.
Polish is a great idea. Just make sure it's completely cleaned off afterward. You want a nice fresh clean finish. Then you want to add LOTS of graphite. (Or some experts now use special pinewood derby oil, which is a little faster and longer lasting.)
I just had a race last night. I utilized many of the tricks I have seen in videos (including yours, thanks :) ) and forums. The car was fast, but the track was Brutal in condition. I jumped the track and it almost happened in a separate lane. My question is, how do we handle tracks that are in very poor condition? What design Changes might I make?
One time i did a pine wood derby with no rules other than it has to fit in your lane, so what i did is i got a drill with fishing line on looped around it and also atached to the pinewood derby car through a hole in the front, needless to say we won and all of our finish times were about 1 second
I think messing with wheel size is asking for trouble. If your rules allow for making wheel alterations, the best is to slice it nice and thin and light.
I got semifinals with a block of wood with a wedge cut off the front. The wedge looked like a right triangle. That finally explains how my block of wood did so well.
Lighter wheels DON'T make the car faster unless it's using an engine, utilizing torque and centrifugal force. Lighter wheels create less resistance to the engine and hence, faster speeds. I believe Michelin did a study and created a lighter wheel by 1 U.S. pound, which makes a vast difference on the race track.
Wrong sport... With an engine there are a lot more factors. In Pinewood, it's all about weight distribution. If you can lighten the wheels (allow them to roll faster off the block) and put that weight on rear of body you are better off.
Weight (or lack thereof) has nothing to do with how fast a wheel rolls down a ramp. It has EVERYTHING to do with Moment of Inertia. You could take a solid cylinder and a hollowed-out cylinder of the same exact size, and the heavier cylinder will roll faster every time. What it really comes down to is how an object's mass is distributed within itself.
I watched a science guy (doctorate level ) prove that the heavier cylinder rolls out faster, just as your test showed, whether you like the results or not.
@@user-kx8rs6vz2o Are you building a pinewood car? If so, you can have light wheels for a winner, or try your heavy wheels and get run off the track. Perhaps the science doesn't equate when we're talking pinewood cars where you are holding up a body and limited to 5oz weight and you need speed. For this, you want light wheels and weight in the body's rear.
so i lighter wheel will roll down the hill faster ?? so the feather hits the ground before the rock? the car its faster with lighter wheels, because you have less kenetic energy in the rotation of the wheels.
Speed = mass x acceleration So on a simple downhill ramp which uses gravity as the as the only other force surely the heavier the wheels will travel at a greater speed?
I'm not sure how to explain the exact kinetic science, but basically a heavier wheel will begin rolling more slowly. However, once the heavier wheel (with more mass) gets rolling, it would roll further. RESULT: Pinewood tracks are short enough that you want a lighter wheel that will start rolling faster. So lighter is better.
The "lighter" wheels, is really less about the actual weight of the wheel, but lowering its "moment of inertia". Because you have taken weight away from the outside, most of its mass is closer to its axis of rotation, which lowers the moment of inertia "I". Rotational Kinetic energy is 1/2 I*w^2. (w being the rotational velocity). If you lower your "I", you use less kinetic energy toward the rotation of the wheels and more in the linear kinetic energy (1/2 m*v^2). Assuming you maintain the same total mass by adding weight back into the car somewhere else, you will have converted all of the saved rotational energy into linear velocity.
Every car has the same engine" a five ounce weight and the same hill to roll down. A builder needs to conserve drag anyplace possible. I like shaved wheels if they are legal. I have used aluminum tape as a washer...works great. Get the axles straight and armorall the wheels. Worked for me and never had a car tossed.
Hi Chanel. Are you really building a pinewood car? The best stuff can be purchased at DerbyDad4Hire. Google it. Then click on "speed supplies." It's about $20 for the good stuff. But before you get oil, you need to make sure you're building an awesome car. Oil will not help if you don't have awesome nails and wheels. Look at my most popular video for good building tips.
Yes, with my little brother... did one for the first time last year, but wanted to improve it more so started researching and came across your video. Thank you for posting it as well in getting back to me. I will definitely look into it since I only knew in using graphite. Thanks again! @@thanethebrain
Hi @@TheChanelCartel ! You're a great big sister! I love it. What other questions do you have or tips do you need? Check out my first video for all you need: "Five tips for fastest pinewood derby - THE ORIGINAL" Follow those tips. That's all you need. I would not waste money on oil. It's expensive, and really, only the pros use it. What you need to do is focus on shining and polishing the axles. That's the #1 most important part. Then follow my other 5 tips and you will do great! I can't promise a win, but you will definitely be near the top. When is the race and where do you live?
hollowing out or lightening the wheels actually makes the car go SLOWER. Its only made up for by the fact that you can add that weight back, further back on the car. Watch this video to see that moment of inertia on pure roll makes no difference the weight, diameter, or width of a solid cylinder, they all traverse space at the same speed, and when you compare solid cylinders to hollow cylinders, solid cylinders always go faster. th-cam.com/video/cB8GNQuyMPc/w-d-xo.html
Interesting video. I watched it, but I'm not sure how to translate this to pinewood wheels. I know from experience that lighter wheels on cars go faster. I'm not 100% sure what the science property would be. But we've timed cars and tested this and it's true. What this video does make me want to do is try melting weight in the wheel so that the rear wheels are solid, and see how that could affect speed.
@@thanethebrain Pretty sure its the two things I said, one the wheels obtain the roll advantage of more central weight distribution, and that weight can be added at the back of the car for added momentum. Weight that would have been circling the axle at a distance and subtracting energy is now only adding energy to pushing the car forward. Shouldn't be too hard to replicate the professor's demonstration with different mods on pinewood wheels. I'd love to find a lecture on wheels with axles rather than just pure roll on cylinders, if I find one i'll let you know.
haha... I've never personally tested this. But my brother had a race for the parents. He said the winning car was a solid piece of lead in the shape of a Hershey's bar. Thin and heavy. Maybe 2 pounds he thought. But also thin and great wheels and axles.
Same concept executed differently- I baked my mostly shaped cars for 2 hours at 250 degrees to lighten them to be able to put more weight in the back. It did not help as much as I expected. I did 3 at once and only reduced the weight by 3-4 grams.
I would think that a light wheel by itself would roll slower than a heavier wheel, as the heavier wheel will convert more potential energy to kinetic. If anything, seems like the primary benefit of light wheels would be to allow you slightly more flexibility to shift more weight to the back of the car.
With three boys, I've been in a few different packs, and have taken the stance that I follow the rules. So if it says nothing about wheels, wheel base, etc, I make the changes. Beware the result: 1. Many parents will say "you cheated." etc. So you need a thick skin. Especially if you win, because everyone will inspect your car to see "how you did it." 2. You can bet the rules next year will be a little more specific. I always offer to help write the rules as I've seen many versions, and can make them as liberal or restrictive as people want.
When I write the rules, I am very thorough to cover all the specifics. My standard cub rules say no extending the wheel base, and no lightening of the wheels. You can sand them for smoothness, but not to make them light.
Most cars will naturally be 3 wheels with all the weight in back. That is a good thing. You can also tilt one of the front axles upward so that the wheel doesn't touch. View my other videos for better tips and explanation.
I've built 25-30 cars. Every once in a while I get a wobble that I just can't get rid of. Here are some tips to try: 1. Put more or less veer in the car. 2. rotate nails to other wheels. 3. Rotate wheels to different spots. 4. Adjust how much angle you have on the nails. Try those things. It sounds like you must have access to a track if you can notice there is now some wobble. Keep making slight adjustments and racing car and tracking times. Last year, I helped a buddy with some speed wobble. He was coming in around 3.150 on his times. We played around and got it running consistently at 3.040. Good enough for about a top 3 finish.
oh... just holding it. That can happen depending on how hard you spin the wheel. (It happens to me often.) If you spin it lighter, I'm sure it rolls smooth. The only real test is once the car is rolling on the track. When the wheel slowly builds up speed and has consistent pressure from weight of the car, only then will you know if there is some wobble. Sorry.
Yes, Zane. As I state early on, "I'm all about following the rules." That said, there are some rules that are very detailed and strict, and others that are pretty much wide open.
Only the washers and sticky nose are a "cheats" in our district. Rules vary by location... know what's allowed in your local race.... don't be a baby about getting beat by someone who knows the rules and uses all the advantages allowed.
You know... it aint in the rules... so maybe it's okay. But the gate drops so fast now, it would need to be very sticky! Yet still small enough not to mess with aerodynamics.
Since mass in not included in the formula for velocity (v=d/t), the lighter wheels won't go faster (as your tests just showed). Physics is such a cruel mistress.
conservation of energy can be written as ME=KE+PE (mechanical energy equals kinetic energy plus potential energy) mass is not in that equation either. Drilled holes make no difference. In a fair race, the only outside acting force on the car is gravity. That means velocity is increasing at the gravitational constant of the earth (9.8 m/s^2). You can calculate acceleration by a=(v2-v1)/(t2-t1) where v1 and v2 are the velocity at the start and finish respectively. t1 and t2 are the start and end time points respectively. Note mass is not in that equation either. If you have taken the first semester of engineering calculus, recall that velocity and acceleration are inextricably linked as the first derivative of velocity is acceleration. If you have not taken calculus, one you are missing out on some cool stuff and two you can safely ignore all this stuff about derivatives as in the paragraph above I put the acceleration formula into its algebraic notation. Regardless, nowhere does mass appear in any of these formulas. Going back to calculus, when you take the derivative of velocity to come up with the acceleration, the only units in play are ones related to distance and time. In taking the derivative of velocity, a unit (such as mass) cannot be in the original function and then appear in the first derivative of that function. Physics for the win. But what about friction you say? Friction between the wheels and the track. Friction between the wheels and its axles. Friction between the surface of the car and the surrounding air. We can safely ignore the effects of friction because I am making the assumption that it is the same car using the same wheels using the same axles bent at the same angles. The only thing that changes is the wheels being drilled out. Any impact friction would have on the race would be identical at the following points: 1. wheels contact patch with the ground 2. wheels contact with the axles 3. air on all of the car except for the wheels. Let's look at the wheels shall we? More to the point, let's look at the aerodynamics of the wheels. In a sealed room with no air currents, solid wheels are more aerodynamic than wheels with holes in them. Once air starts moving, if the air currents are parallel to the wheel, a solid wheel is more aerodynamic. Once the air currents move away from parallel, then the aerodynamics begins to favor wheels that allow air to pass through. When the air current is perpendicular to the wheel, holed wheels are better. In a sealed gym where there are not any air currents to impact the vehicles, solid wheels will slice through the air better than holed wheels (this is why olympic cyclists on short indoor tracks use solid wheels not spoked ones). So to sum, if we ignore the impact of friction on the vehicle, there is no difference between holed and solid wheels. If we allow for friction and aerodynamics to play a role, then under the conditions that most derbies are held (inside in a gym with no moving air currents) solid wheels will have better aerodynamic properties and would actually be expected to be faster than holed wheels all other things being equal. I'm not going to run the hypothetical numbers including friction due to air on the wheels, because the difference in times would probably by in the billionths of seconds i.e. negligible for all practical purposes.
Chris Zimmer actually the formula for kinetic energy of the pinewood car is linear+rotational kinetic energy. K(linear)=1/2 mv^2 & K(rotational)=Iw^2. I is the moment of inertia that is reduced when the mass or location of mass is changed. if the rotational kinetic energy is reduced, the energy goes into linear kinetic energy to balance the equation
The total energy in the system is: K(tot) = K(trans) + K(rot) which can be rewritten as K(tot) = 1/2mv^2 + 1/2Iw^2 as you correctly pointed out Since kinetic and potential energy have to equal we can say the following PE = KE substituting in the above with the original equation gets us PE = 1/2mv^2 + 1/2Iw^2 we also know that PE is just mass times gravitational acceleration times the height or PE = mgh so we can say mgh = 1/2mv^2 + 1/2Iw^2 with m on both sides of the equation, when simplified the masses will cancel each other out. mass will impact rotational momentum if the center of mass is moved closer to the axis of rotation (think figure skater spinning with arms extended versus pulled in against her sides). By drilling holes, the center of mass isn't changed.
Calling them "cheats" rather than 'tips' is not the best descriptive wording. When you are attempting to teach young boys honesty and integrity in Scouting, you would never use the word 'cheat'.
See my other videos for good tips. This was just something fun I did to describe a few things you can look for in OTHER vehicles. Make sure other dads in the race are not cheating. For example, far and away the biggest offender is the extended axels. Most rules say this is not allowed, yet dad's continue to do it anyway and claim they "didn't know."
There is definitely the fact of looking out for others cheating. Next, if we tell the kids that this is cheating, we would hope that with the values we are trying to teach, they wouldn't do it. My final point is that there are OUTLAW class races that these sort of things that would be Cheats in regulation racing are allowed.
Yes... exactly! Did you read my description and watch the full video? I'm showing you some things that may... or may not... be cheating depending on your packs rules.
I am going to have a pinewood derby event for my employees and I did the pinewood derby’s when my kids were younger and nephews (got 1st in all races including the districts & overall, so to many to mention). I appreciate the video bc it’s been about 8yrs and I will have my staff watch your video to help identify cheating (I want all employees to have a fair shot). I will be allowing lighter wheels but that is it! Thanks again
Here's another idea to make it fair... bring them all together and only give them 2 hours to build cars... no testing... just build and then race. Fun and Fair!
no a lighter wheel by itself will not move a car faster while propelled by gravity...... but it will allow more weight you can use at the back of your car. which allows a higher center of gravity = more kinetic energy.
Very good explanation!
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What? It takes more force to move a.1 gram wheel than it does a .05 gram wheel. Heavier= more force to get it to roll
Basic physics says that the mass of the wheel is irrelevant when racing just wheels. it is all about mass distribution. The further the mass is from the axle the slower the it will roll. When you put wheels on a car it does make a difference though -- there you want the least mass rotating (more precisely, the least rotational kinetic energy and so the smallest rotational moment of inertia)
You said it a lot better than I did... or could! Wheels alone don't show the difference. If I had time, I could have demonstrated that with the weight of the car and gravitational pull, the lighter wheels rotate more quickly off the starting block.
@BS STW If you take a heavy wheel vs a light wheel, the heavy wheel will start rolling down the hill slower. A light wheel on a hill will start rolling more quickly because there is not as much mass (weight) to get moving down the hill. Once you get a heavy wheel rolling with all that weight, it will have more power and roll for longer distance; however, the pinewood track is not that long, so it is better to have a LIGHT wheel. (And put the extra weight into the body.)
@@thanethebrain The lighter wheels DO NOT rotate more quickly off the starting block they may rotate more slowly, if the lightening was achieved by hollowing out the rotating body but cannot be made faster by changing weight nor diameter. (nor width).
th-cam.com/video/cB8GNQuyMPc/w-d-xo.html
My kids first year in scouts we just drew on the axels with a pencil and what a difference! We got a tube of graphite this year. Hopefully it helps even more.
Good luck my friend!! YES... load up the wheels with graphite!! #1 tip for speed is working on wheels and axles..
The lighter wheel does not roll faster because it weighs less. It rolls faster because it has a lower moments of inertia. For example, if you took two cylinders made of the same material, one hollow and one solid, the solid cylinder, even though it can weigh significantly more, would roll faster because its mass is more evenly distributed throughout its shape. In this particular case, the lighter wheel rolls faster because its mass is more evenly distributed. What you do not want is for the mass to be concentrated at its circumference. Also, because there is a force applied to the wheel at the axle, the moment of inertia of the wheels becomes less relevant in the context of the greater mass of the entire car.
I think I followed all that. The primary point is that lighter wheels for a pinewood car are definitely better and faster!
@@thanethebrain weight is irrelevant, it could weigh 6 lbs or 6 ounces, if the geometry is the same, it will roll at the same rate. The higher the percentage of mass at the center, the faster it will roll. The 'lightening" is simply removing edge material so that more of the total material is concentrated at the center. If two wheels weighed the exact same, one with spokes and as much weight as possible at the edge, and the other like a discuss with its weight concentrated at the center, the one with the weight at the center will roll faster, even though they weigh the exact same.
@@snap-off5383 I watched the vid you suggested. I would need to try more experiments to test these ideas.
that is true
What size Teflon washers did you use with your cars?
check with DerbyDad4Hire or MaximumVelocity... they have supplies.
If its specifically does NOT state "you can't XXXXX " then YOU CAN... [Smokey Yunick] A lighter rotating mass will accelerate QUICKER= YES......but a pinewood track also has a long flat portion...where the car will decelerates per friction. Having a greater rotational mass will it decelerate SLOWER given the SAME friction. NOW...it is a balancing act between total weight-rotating MASS - friction loss.
The tests are in. There is more benefit to a lighter wheel on the pinewood track. If the track were 100 feet long, then perhaps more mass in the rotating wheel would be better.
Some people use car polish or car wax to polish their axels. Can u then add graphite to those axels/ wheels or will it make it slower like with oil?
Polish is a great idea. Just make sure it's completely cleaned off afterward. You want a nice fresh clean finish. Then you want to add LOTS of graphite. (Or some experts now use special pinewood derby oil, which is a little faster and longer lasting.)
Here is my video on polishing: th-cam.com/video/a3cS56LKXOs/w-d-xo.html
I just had a race last night. I utilized many of the tricks I have seen in videos (including yours, thanks :) ) and forums.
The car was fast, but the track was Brutal in condition. I jumped the track and it almost happened in a separate lane.
My question is, how do we handle tracks that are in very poor condition? What design Changes might I make?
One time i did a pine wood derby with no rules other than it has to fit in your lane, so what i did is i got a drill with fishing line on looped around it and also atached to the pinewood derby car through a hole in the front, needless to say we won and all of our finish times were about 1 second
If you have a smaller wheel in the front. Will that make your car faster or slower? I’m thinking of rotation and resistance.
I think messing with wheel size is asking for trouble. If your rules allow for making wheel alterations, the best is to slice it nice and thin and light.
I got semifinals with a block of wood with a wedge cut off the front. The wedge looked like a right triangle. That finally explains how my block of wood did so well.
Well done my friend!
Lighter wheels DON'T make the car faster unless it's using an engine, utilizing torque and centrifugal force. Lighter wheels create less resistance to the engine and hence, faster speeds. I believe Michelin did a study and created a lighter wheel by 1 U.S. pound, which makes a vast difference on the race track.
Lighter wheels DO make a faster pwd car. I'm guessing that you haven't raced much if at all.
Wrong sport... With an engine there are a lot more factors. In Pinewood, it's all about weight distribution. If you can lighten the wheels (allow them to roll faster off the block) and put that weight on rear of body you are better off.
Weight (or lack thereof) has nothing to do with how fast a wheel rolls down a ramp. It has EVERYTHING to do with Moment of Inertia. You could take a solid cylinder and a hollowed-out cylinder of the same exact size, and the heavier cylinder will roll faster every time. What it really comes down to is how an object's mass is distributed within itself.
too much science for me... lol
I watched a science guy (doctorate level ) prove that the heavier cylinder rolls out faster, just as your test showed, whether you like the results or not.
@@user-kx8rs6vz2o Are you building a pinewood car? If so, you can have light wheels for a winner, or try your heavy wheels and get run off the track. Perhaps the science doesn't equate when we're talking pinewood cars where you are holding up a body and limited to 5oz weight and you need speed. For this, you want light wheels and weight in the body's rear.
so i lighter wheel will roll down the hill faster ??
so the feather hits the ground before the rock?
the car its faster with lighter wheels, because you have less kenetic energy in the rotation of the wheels.
Exactly... lighter wheels have less mass to get rolling and will move faster.
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Lol feather and rock mixing the metaphor a bit but I get where you’re going.
This is the first I've heard of an extended wheel base making a car go faster. Why does the distance between the axles make the car go faster?
Two reasons... 1. more stability throughout the car. 2. ability to get weight a tiny bit further back.
Speed = mass x acceleration
So on a simple downhill ramp which uses gravity as the as the only other force surely the heavier the wheels will travel at a greater speed?
I'm not sure how to explain the exact kinetic science, but basically a heavier wheel will begin rolling more slowly. However, once the heavier wheel (with more mass) gets rolling, it would roll further. RESULT: Pinewood tracks are short enough that you want a lighter wheel that will start rolling faster. So lighter is better.
Speed doesn't = mass x acceleration. Force does. F=ma. Speed = acceleration x time.
The "lighter" wheels, is really less about the actual weight of the wheel, but lowering its "moment of inertia". Because you have taken weight away from the outside, most of its mass is closer to its axis of rotation, which lowers the moment of inertia "I". Rotational Kinetic energy is 1/2 I*w^2. (w being the rotational velocity). If you lower your "I", you use less kinetic energy toward the rotation of the wheels and more in the linear kinetic energy (1/2 m*v^2). Assuming you maintain the same total mass by adding weight back into the car somewhere else, you will have converted all of the saved rotational energy into linear velocity.
Every car has the same engine" a five ounce weight and the same hill to roll down.
A builder needs to conserve drag anyplace possible.
I like shaved wheels if they are legal.
I have used aluminum tape as a washer...works great.
Get the axles straight and armorall the wheels.
Worked for me and never had a car tossed.
What kind of oil lubricant exactly should be used? Would car oil work just as good?
Hi Chanel. Are you really building a pinewood car? The best stuff can be purchased at DerbyDad4Hire. Google it. Then click on "speed supplies." It's about $20 for the good stuff. But before you get oil, you need to make sure you're building an awesome car. Oil will not help if you don't have awesome nails and wheels. Look at my most popular video for good building tips.
Yes, with my little brother... did one for the first time last year, but wanted to improve it more so started researching and came across your video. Thank you for posting it as well in getting back to me. I will definitely look into it since I only knew in using graphite. Thanks again! @@thanethebrain
Hi @@TheChanelCartel ! You're a great big sister! I love it. What other questions do you have or tips do you need? Check out my first video for all you need: "Five tips for fastest pinewood derby - THE ORIGINAL" Follow those tips. That's all you need. I would not waste money on oil. It's expensive, and really, only the pros use it. What you need to do is focus on shining and polishing the axles. That's the #1 most important part. Then follow my other 5 tips and you will do great! I can't promise a win, but you will definitely be near the top. When is the race and where do you live?
hollowing out or lightening the wheels actually makes the car go SLOWER. Its only made up for by the fact that you can add that weight back, further back on the car. Watch this video to see that moment of inertia on pure roll makes no difference the weight, diameter, or width of a solid cylinder, they all traverse space at the same speed, and when you compare solid cylinders to hollow cylinders, solid cylinders always go faster.
th-cam.com/video/cB8GNQuyMPc/w-d-xo.html
Interesting video. I watched it, but I'm not sure how to translate this to pinewood wheels. I know from experience that lighter wheels on cars go faster. I'm not 100% sure what the science property would be. But we've timed cars and tested this and it's true. What this video does make me want to do is try melting weight in the wheel so that the rear wheels are solid, and see how that could affect speed.
@@thanethebrain Pretty sure its the two things I said, one the wheels obtain the roll advantage of more central weight distribution, and that weight can be added at the back of the car for added momentum. Weight that would have been circling the axle at a distance and subtracting energy is now only adding energy to pushing the car forward. Shouldn't be too hard to replicate the professor's demonstration with different mods on pinewood wheels. I'd love to find a lecture on wheels with axles rather than just pure roll on cylinders, if I find one i'll let you know.
@@snap-off5383 Yes... please share if you find any such vids.... lots of small tweeks that could be further experimented.
We have a open division for parents. No weight rule. What is a good weight to shoot for if you can weigh more than 5oz.
haha... I've never personally tested this. But my brother had a race for the parents. He said the winning car was a solid piece of lead in the shape of a Hershey's bar. Thin and heavy. Maybe 2 pounds he thought. But also thin and great wheels and axles.
I microwaved mine to dry out the wood. Dont know if it helped, but i won for my group.
hmmm... that's a new one. Nice work.
Same concept executed differently- I baked my mostly shaped cars for 2 hours at 250 degrees to lighten them to be able to put more weight in the back. It did not help as much as I expected. I did 3 at once and only reduced the weight by 3-4 grams.
@@mark-x2375 I've never tried the baking... but I've heard others do it.
What about awana grand prix cars
Should be the same as pinewood. As long as there is a center rail for the cars, you can use the tips in my "ORIGINAL" video.
I would think that a light wheel by itself would roll slower than a heavier wheel, as the heavier wheel will convert more potential energy to kinetic. If anything, seems like the primary benefit of light wheels would be to allow you slightly more flexibility to shift more weight to the back of the car.
Bob Papadopoulos you sound a lot smarter than me!!
if it doesnt say anything in the rules about wheel modification, is it fair game?
With three boys, I've been in a few different packs, and have taken the stance that I follow the rules. So if it says nothing about wheels, wheel base, etc, I make the changes. Beware the result: 1. Many parents will say "you cheated." etc. So you need a thick skin. Especially if you win, because everyone will inspect your car to see "how you did it." 2. You can bet the rules next year will be a little more specific. I always offer to help write the rules as I've seen many versions, and can make them as liberal or restrictive as people want.
When I write the rules, I am very thorough to cover all the specifics. My standard cub rules say no extending the wheel base, and no lightening of the wheels. You can sand them for smoothness, but not to make them light.
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How do you make it that your car is only on 3 wheels?
Most cars will naturally be 3 wheels with all the weight in back. That is a good thing. You can also tilt one of the front axles upward so that the wheel doesn't touch. View my other videos for better tips and explanation.
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I polish my axles and now they speed wobble when I test them what causes that. they did not speed wobble before I polish them.
I've built 25-30 cars. Every once in a while I get a wobble that I just can't get rid of. Here are some tips to try: 1. Put more or less veer in the car. 2. rotate nails to other wheels. 3. Rotate wheels to different spots. 4. Adjust how much angle you have on the nails. Try those things. It sounds like you must have access to a track if you can notice there is now some wobble. Keep making slight adjustments and racing car and tracking times. Last year, I helped a buddy with some speed wobble. He was coming in around 3.150 on his times. We played around and got it running consistently at 3.040. Good enough for about a top 3 finish.
Thane Walton when I hold the axle with my fingers and spin the tires the tire wobbles on the axle have not put on car yet
oh... just holding it. That can happen depending on how hard you spin the wheel. (It happens to me often.) If you spin it lighter, I'm sure it rolls smooth. The only real test is once the car is rolling on the track. When the wheel slowly builds up speed and has consistent pressure from weight of the car, only then will you know if there is some wobble. Sorry.
Thane Walton okay thanks that's what I thought but I wasn't sure thanks again for your help
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Everything has to be Bsa approved for the pinewood derby
Yes, Zane. As I state early on, "I'm all about following the rules." That said, there are some rules that are very detailed and strict, and others that are pretty much wide open.
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cubs scout 1979 finished 9th in the Montgomery county finals. I received a spark plug trophy. I Believe the field was around 180 scouts.
Did you use any of the cheats to help you win? :-)
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My dad was telling me about how thay raced. Single elimination 4lane 180 scouts
Great video, thank you. But wouldn’t you agree you are scratching the surface? Didn’t we all learn these basics in the Mark Rober video?
Why should one wheel be slightly off the ground?
ChewTube
Less Friction
Exactly... 1/4 less friction. Watch my ORIGINAL video for all the best tips and more explanation. th-cam.com/video/rBWOpeR9A6g/w-d-xo.html&t
That wheel test was a fail 😂
haha... yes indeed, Juan. I should have practiced that and redid the test so it came out correct.
3:36 cap 🧢 😂😂😂😂😂💀
Only the washers and sticky nose are a "cheats" in our district. Rules vary by location... know what's allowed in your local race.... don't be a baby about getting beat by someone who knows the rules and uses all the advantages allowed.
What do you put on the car to make it a sticky nose
Any sticky substance that doesn't show very much. rubber cement, molasses, etc. :-)
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Sehr interessant. Das ist ein schönes Hobby :-)
tues selber Danke schoen mein freund!!
oh nice i got a big fat F for my GTT ( gate away to technology)
ahhh the ol sticky nose
You know... it aint in the rules... so maybe it's okay. But the gate drops so fast now, it would need to be very sticky! Yet still small enough not to mess with aerodynamics.
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Your name is Thang??? That's an awesome name!!
Yes.. Wild Thang! haha.... well... almost. It's actually Thane. Thanks bro!
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Since mass in not included in the formula for velocity (v=d/t), the lighter wheels won't go faster (as your tests just showed). Physics is such a cruel mistress.
Chris Zimmer, wrong law. conservation of energy. less rotational mass = more energy into linear velocity
conservation of energy can be written as ME=KE+PE (mechanical energy equals kinetic energy plus potential energy) mass is not in that equation either. Drilled holes make no difference.
In a fair race, the only outside acting force on the car is gravity. That means velocity is increasing at the gravitational constant of the earth (9.8 m/s^2). You can calculate acceleration by a=(v2-v1)/(t2-t1) where v1 and v2 are the velocity at the start and finish respectively. t1 and t2 are the start and end time points respectively. Note mass is not in that equation either.
If you have taken the first semester of engineering calculus, recall that velocity and acceleration are inextricably linked as the first derivative of velocity is acceleration. If you have not taken calculus, one you are missing out on some cool stuff and two you can safely ignore all this stuff about derivatives as in the paragraph above I put the acceleration formula into its algebraic notation. Regardless, nowhere does mass appear in any of these formulas. Going back to calculus, when you take the derivative of velocity to come up with the acceleration, the only units in play are ones related to distance and time. In taking the derivative of velocity, a unit (such as mass) cannot be in the original function and then appear in the first derivative of that function. Physics for the win.
But what about friction you say? Friction between the wheels and the track. Friction between the wheels and its axles. Friction between the surface of the car and the surrounding air. We can safely ignore the effects of friction because I am making the assumption that it is the same car using the same wheels using the same axles bent at the same angles. The only thing that changes is the wheels being drilled out. Any impact friction would have on the race would be identical at the following points:
1. wheels contact patch with the ground
2. wheels contact with the axles
3. air on all of the car except for the wheels.
Let's look at the wheels shall we? More to the point, let's look at the aerodynamics of the wheels. In a sealed room with no air currents, solid wheels are more aerodynamic than wheels with holes in them. Once air starts moving, if the air currents are parallel to the wheel, a solid wheel is more aerodynamic. Once the air currents move away from parallel, then the aerodynamics begins to favor wheels that allow air to pass through. When the air current is perpendicular to the wheel, holed wheels are better. In a sealed gym where there are not any air currents to impact the vehicles, solid wheels will slice through the air better than holed wheels (this is why olympic cyclists on short indoor tracks use solid wheels not spoked ones).
So to sum, if we ignore the impact of friction on the vehicle, there is no difference between holed and solid wheels. If we allow for friction and aerodynamics to play a role, then under the conditions that most derbies are held (inside in a gym with no moving air currents) solid wheels will have better aerodynamic properties and would actually be expected to be faster than holed wheels all other things being equal. I'm not going to run the hypothetical numbers including friction due to air on the wheels, because the difference in times would probably by in the billionths of seconds i.e. negligible for all practical purposes.
Chris Zimmer actually the formula for kinetic energy of the pinewood car is linear+rotational kinetic energy. K(linear)=1/2 mv^2 & K(rotational)=Iw^2. I is the moment of inertia that is reduced when the mass or location of mass is changed. if the rotational kinetic energy is reduced, the energy goes into linear kinetic energy to balance the equation
The total energy in the system is:
K(tot) = K(trans) + K(rot) which can be rewritten as
K(tot) = 1/2mv^2 + 1/2Iw^2 as you correctly pointed out
Since kinetic and potential energy have to equal we can say the following
PE = KE
substituting in the above with the original equation gets us
PE = 1/2mv^2 + 1/2Iw^2
we also know that PE is just mass times gravitational acceleration times the height or
PE = mgh so we can say
mgh = 1/2mv^2 + 1/2Iw^2
with m on both sides of the equation, when simplified the masses will cancel each other out.
mass will impact rotational momentum if the center of mass is moved closer to the axis of rotation (think figure skater spinning with arms extended versus pulled in against her sides). By drilling holes, the center of mass isn't changed.
Chris Zimmer the problem with that theory is that m (mass) is not the same thing as I (moment of inertia) and do not cancel each other.
Calling them "cheats" rather than 'tips' is not the best descriptive wording. When you are attempting to teach young boys honesty and integrity in Scouting, you would never use the word 'cheat'.
See my other videos for good tips. This was just something fun I did to describe a few things you can look for in OTHER vehicles. Make sure other dads in the race are not cheating. For example, far and away the biggest offender is the extended axels. Most rules say this is not allowed, yet dad's continue to do it anyway and claim they "didn't know."
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There is definitely the fact of looking out for others cheating.
Next, if we tell the kids that this is cheating, we would hope that with the values we are trying to teach, they wouldn't do it.
My final point is that there are OUTLAW class races that these sort of things that would be Cheats in regulation racing are allowed.
my daughter won every year for school
Awesome! Well done!
Apparently, cheaters can spell axle correctly. "Trust me..."?
Carry it up bro
Let's go win this thing!
DUDE!!!! Don't cheat!
Yes... exactly! Did you read my description and watch the full video? I'm showing you some things that may... or may not... be cheating depending on your packs rules.
But the heavy wheel has more potential energy when rolling down a slope
I instald nitros
That will do it!
bob
Yo Bob!
CHEATER !!! NO CHEATING
That's right. "I'm all about following the rules." So keep an eye out for these tricks that other racers might be using!
And wat if he wants to make it his hobby like models now that's not considered cheating
But right if comes to scouts
Bee fest
r
A+
Thx mate
Gave a like cool vid
cooi
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Don't cheat so disappointed...XD
That's right, Jake. Cheaters never prosper. I was just making a video to point out some things that you can watch out for so others don't do it.
You relies that I was joking right. XD means dying laughing
Lol
@@jacobwalton4109 WOW! I've always seen XD, but no one has ever said exactly what it meant. Thank you.
nise
Yes! Nice, Nise, Noise, Noice... whatever you say, my friend!
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