This guy gets ripped on an awful lot for the direction of the acceleration of gravity. The way he does it makes perfect sense, if you like finding negative times, be my guest. Thanks for the videos!
Watching from New Zealand with my Physics exam in two days. You have no idea how much of a lifesaver you are! Totally get projectile motion now thank-you SO much! The accent helps too - very cool ;)
you are really good at explaining everything. i was confused before i started watching your videos. you made projectile motion really easy for me. thank you very much. looking forward to watching more of your videos as the semester continues
gravity is always in downward direction making it +9.8m/s2 if it is against gravity its -9.8m/s2 it's semantics. but if you are considering the coordinates in the Cartesian plane x axis from the origin to the right +, from the origin to the left - . y axis from the origin upward + from the origin downward -
Please come teach instead of our current teacher. I'm staying home today because I have a Physics test and he didn't teach anything- so I'm spending my day studying your videos.
@reemoo123 Each problem is different, and how you approach it depends on the info that you are given. In this case, with the given info, it made sense to start the other way.
I don’t understand how you know to calculate for time first. As a novice attempting these problems, unless the problem asks for time, I would not think to solve for it.
Can you do an example of this doing this problem You are walking around your neighborhood and you see a child on top of a roof of a building kick a soccer ball. The soccer ball is kicked at 49° from the edge of the building with an initial velocity of 19 m/s and lands 57 meters away from the wall. How tall is the building that the child is standing on?
@derekowens, shouldn't time at 4:20 be half that time since we are only looking for the peak height? so instead of 2seconds use 1 second. Does anybody else see what I'm saying?
+coldgatorademan its a matter of choice. you can just leave it and the final answer would be the same. perhaps he is just comfortable doing it that way
Can anyone explain me when should we use the value of acceleration due to gravity negative or positive?? That negative and positive sign always get me in problem
I'll try to explain. In general, you can consider up or down, one direction or the other, to be the positive direction. Just pick one, but stick with that convention for the entire problem. In this case, I chose down to be positive, and since gravity always pulls down, gravity in positive 9.8. If I had chosen up to be positive, then gravity would be -9.8 in this problem.
Yes, you are right that gravity's acceleration is 9.8 m/s^2. But in this particular case, you may find that he stated with a directional arrow that any motion towards the ground will be considered as a positive value. Meaning in this particular instance 9.8 is positive. In the real world it's negative. But because this is a theoretical question, he can state whatever direction he wants to be positive which he clearly demonstrated in his explanation. He is treating the acceleration of gravity as a positive answer, meaning that any upward motion is treated as a negative, This does not alter the final answer in any which way.
i have to admit that his drawing is very decent
I literally come back here everytime i have a Physics Final, and you never fail to impress me. Been here 11th Grade, and Freshman College Year!
This guy gets ripped on an awful lot for the direction of the acceleration of gravity.
The way he does it makes perfect sense, if you like finding negative times, be my guest.
Thanks for the videos!
Holy cow, I calculated it before watching and I got it right xD
Thankyou So much Man. Youve been amazing, needed so much help understanding concepts and all your videos have been exactly what i was looking for!!
Watching from New Zealand with my Physics exam in two days. You have no idea how much of a lifesaver you are! Totally get projectile motion now thank-you SO much! The accent helps too - very cool ;)
you are really good at explaining everything. i was confused before i started watching your videos. you made projectile motion really easy for me. thank you very much. looking forward to watching more of your videos as the semester continues
you are a godsend. thank you so much for posting these videos!!
thank u sooooooo mcuh, u hav no idea how much u helped me and my friends for our yr 12 physics topic
gravity is always in downward direction making it +9.8m/s2 if it is against gravity its -9.8m/s2 it's semantics. but if you are considering the coordinates in the Cartesian plane x axis from the origin to the right +, from the origin to the left - .
y axis from the origin upward + from the origin downward -
What if they gave you the height of the cliff, but they ask you to find the distance from the cliff that speedy lands?
you are the best
Great video this was really helpful!
Thank You very much! I understood the topic by watching your videos. :)
Please come teach instead of our current teacher. I'm staying home today because I have a Physics test and he didn't teach anything- so I'm spending my day studying your videos.
@reemoo123 Each problem is different, and how you approach it depends on the info that you are given. In this case, with the given info, it made sense to start the other way.
I don’t understand how you know to calculate for time first. As a novice attempting these problems, unless the problem asks for time, I would not think to solve for it.
Can you do an example of this doing this problem
You are walking around your neighborhood and you see a child on top of a roof of a building kick a soccer ball. The soccer ball is kicked at 49° from the edge of the building with an initial velocity of 19 m/s and lands 57 meters away from the wall. How tall is the building that the child is standing on?
May you please make a jetfighter launching a missle to a stationary target video?
Thank you.
@derekowens, shouldn't time at 4:20 be half that time since we are only looking for the peak height? so instead of 2seconds use 1 second. Does anybody else see what I'm saying?
does it mean that we must always start in vertical?
I got the wrong answer because i used x-x0= 1/2(v0+v)t and i got 4 seconds instead of 2s. I assumed that v is equal to zero 🤧
Woow !
thanks speedy!!!!
what is the point of making down positive to get a positive 9.8m/s^2 why can't you just leave it and have -9.8m/s^2 can someone explain this to me?
+coldgatorademan its a matter of choice. you can just leave it and the final answer would be the same. perhaps he is just comfortable doing it that way
Sx=Uxt
U will get t
t = root 2h/g
U will get h
Poor speedy...
Plz sir can u give another example
the height is 9.8......... (1/2)(9.8)(2)= 9.8
You forgot the square on the 2 bruh
my bad, sorry bout that, thanks for the info ☺
No prob :)
Y=9.8
that drawing is literally killing me hahah
Can anyone explain me when should we use the value of acceleration due to gravity negative or positive??
That negative and positive sign always get me in problem
I'll try to explain. In general, you can consider up or down, one direction or the other, to be the positive direction. Just pick one, but stick with that convention for the entire problem. In this case, I chose down to be positive, and since gravity always pulls down, gravity in positive 9.8. If I had chosen up to be positive, then gravity would be -9.8 in this problem.
@@derekowens Thanks. I think I understood what you said. I'll try some problems so as not to forget this.
you said we should start with the vertical first then the horizontal , how come in this problem it's the opposite ?
I LOVE YOU. :')
Hello EL
Lmao this drawing
Wrong. Acceleration is -9.8 m/s^2
He stated that down was positive, so he's right.
Wrong. Acceleration by gravity is always -9.8. Go to school.
Yes, you are right that gravity's acceleration is 9.8 m/s^2. But in this particular case, you may find that he stated with a directional arrow that any motion towards the ground will be considered as a positive value. Meaning in this particular instance 9.8 is positive. In the real world it's negative. But because this is a theoretical question, he can state whatever direction he wants to be positive which he clearly demonstrated in his explanation. He is treating the acceleration of gravity as a positive answer, meaning that any upward motion is treated as a negative, This does not alter the final answer in any which way.
LizardanNet . Which direction we consider to be positive, up or down, is ultimately arbitrary. The problem can be solved correctly either way.