Am I wrong or the teacher?

  • Thread starter -Physician
  • Start date
  • #1
85
0
Okay, so our teacher gave us to define s=vt. Now i did it like that:
s=vt=(v_0+at)t=v_0 t+at2, but then, teacher said that's wrong, it should give you s=v_0 t+ \frac{1}{2} at2 Who is wrong me or teacher, If I am wrong, tell me where is my mistake, if the teacher is wrong let me know, thanks!
 
Last edited:

Answers and Replies

  • #2
4
0
I am assuming that this is a problem concerning the motion of a particle under uniform acceleration. In that case, the teacher is correct. The equation ## s = vt ## is only correct for constant velocity. If velocity is not constant, then you must replace ## v ## with the average velocity.

Under uniform acceleration, the average velocity is simply ##\frac{v_0+v_f}{2}##.
 
  • #3
berkeman
Mentor
60,006
10,208
Okay, so our teacher gave us to define s=vt. Now i did it like that:
s=vt=(v0+at)t=v0t+at^2, but then, teacher said that's wrong, it should give you s=v0t+1/2at^2. Who is wrong me or teacher, If I am wrong, tell me where is my mistake, if the teacher is wrong let me know, thanks!

You are wrong.

Are you familiar with calculus? Derivatives and integrals? That's one way to derive those equations.
 
  • #4
85
0
I am assuming that this is a problem concerning the motion of a particle under uniform acceleration. In that case, the teacher is correct. The equation ## s = vt ## is only correct for constant velocity. If velocity is not constant, then you must replace ## v ## with the average velocity.

Under uniform acceleration, the average velocity is simply ##\frac{v_0+v_f}{2}##.
So that would be ##s=vt=\frac{v_0+v_f}{2}t=v_0 t + \frac{1}{2}##at2 or ##s=vt=\frac{v_0+v_f}{2}t=v_f t - \frac{1}{2}##at2
 
Last edited:
  • #5
4
0
So that would be ##s=vt=\frac{v_0+v_f}{2}t=v_0 t + \frac{1}{2}## at2 or ##s=vt=\frac{v_0+v_f}{2}t=v_f t - \frac{1}{2}## at2

Right?
Yes that is correct.
 

Related Threads on Am I wrong or the teacher?

  • Last Post
Replies
7
Views
2K
  • Last Post
Replies
5
Views
9K
  • Last Post
Replies
3
Views
8K
  • Last Post
Replies
3
Views
1K
Replies
15
Views
3K
  • Last Post
Replies
8
Views
2K
  • Last Post
Replies
5
Views
2K
  • Last Post
Replies
2
Views
1K
  • Last Post
Replies
1
Views
1K
Top