Using Newton’s Second Law to solve for the Force of Friction between a Dynamics Cart and Track. Is friction really negligible? Also, publishing today’s video marks an interesting Flipping Physics milestone. It means there are now more than 100 hours of me teaching on the internet. 17 Hours of edited Billy, Bobby and Bo videos, 79 hours of in-class lectures and 4 hours of presentations. Wow, that’s a lot of mr.p. #PhysicsED #flipclass
Mr. P, thank you so much for creating Flipping Physics! If it weren't for these videos, I would be doing really poorly in my Physics 1 class, and would be incredibly stressed. So thank you!
Your videos really helped me. I'm not understanding physics but when I watch your videos I've started loving physics. Please can you create videos on quantum mechanics. And some calculas
Thanks! Sorry, I do not plan to make any videos specifically about quantum mechanics at this time. I am concentrating on the AP Physics 1 curriculum right now. I do have videos about calculus based physics: www.flippingphysics.com/ap-physics-c-review.html But not Calculus specifically.
Flipping Physics. Mr. P we your videos really helped me but I'm still getting problem in calculas and vector please please please create videos on that topic please please please please please please please please please please please Mr p
What's wrong with getting the acceleration by using the v-final minus v-initial over time. with v initial being 0 and v- final being the displacement of 0.52 meters over 1.15 seconds = 0.452 m/s. a= (0.452-0)/1.15 = 0.393 m/s^2 ... why is it wrong?
Average velocity equals displacement over change in time. Velocity final is an instantaneous velocity, which is not the same as average velocity. Here is a video about the difference between the two: www.flippingphysics.com/instantaneous-and-average-velocity.html
In general, when the force is pretty close to constant, you can consider it to be constant. In the next video: www.flippingphysics.com/force-vs-time.html I show three sections: Blue and Red are clearly constant, and yellow is clearly not constant.
This seems more convoluted than it needs to be. Why not use a motion detector, and use the slope of the velocity graph to get the acceleration? That way the acceleration is also found experimentally, and we don't need to make additional assumptions like constant acceleration (to use UAM) since we can just see the velocity graph is linear and get the acceleration directly.
There are usually multiple ways to solve physics problems and absolutely, one could find the acceleration using a motion detector and use the velocity as a function of time. Instead of using a motion sensor, we could also measure the final velocity using the photogate, with velocity initial of zero and the change in time we can determine the acceleration. I wanted to show an actual measurement of a force as a function of time and I already have many videos about UAM. The point wasn't really to find acceleration, the point was to understand Newton's Second Law and I thought it would be fun to find the force of friction between the cart and the track. Also, I have another video in the works which is an extension of this one. That video will explain why the tension force in the string changes as a function of time even though the free body diagram on the mass hanging doesn't change, which is often a stumbling block for students.
We Are Showboat Glad you enjoy the videos. By the way, thanks for the suggestion on how to solve this problem. It reminded my that I need to reflect more on how I solve problems for my videos to see if there is an alternate, useful solution. Sometimes the one that occurs to me first isn't the best one and the more variety I have in my solutions, the better the education will be. So thanks.
Mr.P when calculating for the force using mass times acceleration in the x direction, how come you only used the mass of the cart (.613kg) instead of adding both masses (.613kg+.055kg). ik they are in the same system but how do you know which situation you only focus on 1 mass and which you focus on both. is the acceleration not the same for both or am i mixing things here?
The acceleration is the same for both the cart and the hanging mass. The force sensor is attached to the cart, therefore, the force measured is the force applied to the cart. This is why we summed the forces acting on the cart only. You can also sum the forces on the system (cart and hanging mass), however, that was not the approach I took in this video.
Newton's Second Law of Motion needs a slight correction since they did not know about squaring a number in Newton's era we can assume that this may have been overlooked. As such (F=ma^2) is a natural correction that can be easily proofed through calculation, formulation, and experimentation. This correction is 33% more accurate if you do not accept it proof it yourself.
I don't understand how you go from one equation: (UAM) to 2 times the change of displacement in the x direction divided by the change in time squared...
+Fathom XalxTV I don't understand @ 6:15 Bobby describes the UAM equation and how he uses algebra to rearrange it to solve for acceleration in the x-direciton. It's algebra and knowing the initial velocity of the cart is zero. What _exactly_ is confusing you?
+Flipping Physics Hi! I love how you reply to your subscribers! I don't understand how he rearranges the uam to solve for acceleration, is it just reversed?
+Fathom XalxTV No, it is not just reversed. Δx=(Vi)(Δt)+(1/2)(a)Δt^2 with an initial velocity of zero becomes Δx=(1/2)(a)Δt^2 multiply through by 2 and switch sides gives (a)Δt^2=2Δx then divide by Δt^2 to get a=(2Δx)/(Δt^2). However, it confuses me that you are asking this because this is exactly what Bobby describes in the video which is why I make the videos because it is so annoying to try to write things like this out in a comment of a TH-cam video. Did any of that help?
+Flipping Physics I understand, i didnt mean to make your day any harder than what it is. I believe I lack comprehension for this equation due to the fact that I suffered in algebra. Thank you though, I understand now, I had my dad explain it to me. Thank you!! These videos help me a lot with what my physics work
+Fathom XalxTV No worries about my day. Sorry I seemed put off. Now I understand it is the algebra which is tripping you up. Glad to know I can help you ... and your dad as well :)
Man, this guy deserves more views with the amount of work he does.
Yep, I can agree with that.
Force times the displacement? 😂
Using Newton’s Second Law to solve for the Force of Friction between a Dynamics Cart and Track. Is friction really negligible?
Also, publishing today’s video marks an interesting Flipping Physics milestone. It means there are now more than 100 hours of me teaching on the internet. 17 Hours of edited Billy, Bobby and Bo videos, 79 hours of in-class lectures and 4 hours of presentations. Wow, that’s a lot of mr.p. #PhysicsED #flipclass
Mr. P, thank you so much for creating Flipping Physics! If it weren't for these videos, I would be doing really poorly in my Physics 1 class, and would be incredibly stressed. So thank you!
+Katelyn Douay Ahhhhh, reducing stress. so nice.
Thank you so much for making these videos! You saved my life! God Bless you, keep on making these videos
You are welcome. Keep liking the videos and leaving awesome comments like this one. It will help me "keep on making these videos"!
The voice of the student on the left reminds me of SpongeBob's voice. Great vids, thank you! :)
Thank you for help us mr p so good explanation
+Gholam Mustafa Ali As always, you are welcome.
Your videos really helped me. I'm not understanding physics but when I watch your videos I've started loving physics. Please can you create videos on quantum mechanics. And some calculas
Thanks! Sorry, I do not plan to make any videos specifically about quantum mechanics at this time. I am concentrating on the AP Physics 1 curriculum right now. I do have videos about calculus based physics: www.flippingphysics.com/ap-physics-c-review.html But not Calculus specifically.
Flipping Physics. Mr. P we your videos really helped me but I'm still getting problem in calculas and vector please please please create videos on that topic please please please please please please please please please please please Mr p
nice work i enjoyed learning too ; )
What do you write on the paper while filming as the students?
Sir, can use an electronic hanging spring scale, instead of the force meter?
What's wrong with getting the acceleration by using the v-final minus v-initial over time. with v initial being 0 and v- final being the displacement of 0.52 meters over 1.15 seconds = 0.452 m/s.
a= (0.452-0)/1.15 = 0.393 m/s^2 ... why is it wrong?
Average velocity equals displacement over change in time. Velocity final is an instantaneous velocity, which is not the same as average velocity. Here is a video about the difference between the two: www.flippingphysics.com/instantaneous-and-average-velocity.html
Why do you assume net force to be constant? How do you know when forces will be constant so that you can use uniformly accelerated motion equations?
In general, when the force is pretty close to constant, you can consider it to be constant. In the next video: www.flippingphysics.com/force-vs-time.html I show three sections: Blue and Red are clearly constant, and yellow is clearly not constant.
This seems more convoluted than it needs to be. Why not use a motion detector, and use the slope of the velocity graph to get the acceleration? That way the acceleration is also found experimentally, and we don't need to make additional assumptions like constant acceleration (to use UAM) since we can just see the velocity graph is linear and get the acceleration directly.
There are usually multiple ways to solve physics problems and absolutely, one could find the acceleration using a motion detector and use the velocity as a function of time. Instead of using a motion sensor, we could also measure the final velocity using the photogate, with velocity initial of zero and the change in time we can determine the acceleration.
I wanted to show an actual measurement of a force as a function of time and I already have many videos about UAM. The point wasn't really to find acceleration, the point was to understand Newton's Second Law and I thought it would be fun to find the force of friction between the cart and the track.
Also, I have another video in the works which is an extension of this one. That video will explain why the tension force in the string changes as a function of time even though the free body diagram on the mass hanging doesn't change, which is often a stumbling block for students.
Can't wait to see it. I love these videos.
We Are Showboat Glad you enjoy the videos. By the way, thanks for the suggestion on how to solve this problem. It reminded my that I need to reflect more on how I solve problems for my videos to see if there is an alternate, useful solution. Sometimes the one that occurs to me first isn't the best one and the more variety I have in my solutions, the better the education will be. So thanks.
You are the best
Mr.P when calculating for the force using mass times acceleration in the x direction, how come you only used the mass of the cart (.613kg) instead of adding both masses (.613kg+.055kg). ik they are in the same system but how do you know which situation you only focus on 1 mass and which you focus on both. is the acceleration not the same for both or am i mixing things here?
The acceleration is the same for both the cart and the hanging mass.
The force sensor is attached to the cart, therefore, the force measured is the force applied to the cart. This is why we summed the forces acting on the cart only.
You can also sum the forces on the system (cart and hanging mass), however, that was not the approach I took in this video.
Newton's Second Law of Motion needs a slight correction since they did not know about squaring a number in Newton's era we can assume that this may have been overlooked. As such (F=ma^2) is a natural correction that can be easily proofed through calculation, formulation, and experimentation. This correction is 33% more accurate if you do not accept it proof it yourself.
Mr p are you on Twitter
+Owez Khan's Science Yep. @FlippingPhysics
can you review my problem let me know f I made any mistakes. thanks.
I don't understand how you go from one equation: (UAM) to 2 times the change of displacement in the x direction divided by the change in time squared...
+Fathom XalxTV I don't understand @ 6:15 Bobby describes the UAM equation and how he uses algebra to rearrange it to solve for acceleration in the x-direciton. It's algebra and knowing the initial velocity of the cart is zero. What _exactly_ is confusing you?
+Flipping Physics Hi! I love how you reply to your subscribers! I don't understand how he rearranges the uam to solve for acceleration, is it just reversed?
+Fathom XalxTV No, it is not just reversed. Δx=(Vi)(Δt)+(1/2)(a)Δt^2 with an initial velocity of zero becomes Δx=(1/2)(a)Δt^2 multiply through by 2 and switch sides gives (a)Δt^2=2Δx then divide by Δt^2 to get a=(2Δx)/(Δt^2).
However, it confuses me that you are asking this because this is exactly what Bobby describes in the video which is why I make the videos because it is so annoying to try to write things like this out in a comment of a TH-cam video.
Did any of that help?
+Flipping Physics I understand, i didnt mean to make your day any harder than what it is. I believe I lack comprehension for this equation due to the fact that I suffered in algebra. Thank you though, I understand now, I had my dad explain it to me. Thank you!! These videos help me a lot with what my physics work
+Fathom XalxTV No worries about my day. Sorry I seemed put off. Now I understand it is the algebra which is tripping you up. Glad to know I can help you ... and your dad as well :)
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Ma formula for force 🤣🤣🤣🤣🤣🤣🤣🤣🤣