# Velocity vs. time graphs need help

1. Sep 15, 2011

### Arlene87

i am trying to do my physics lab tutorial homework and i am confused about a question that asks..

bill got his distance and acceleration graph right but drew the incorrect velocity vs. time graph shown here.

velocity
|
| / | |\
| / | | \
|_ /__|______ |__\___>
time

((sorry for my crappy triangles lol))

1why.do you think bill made this mistake? what advice would you give him to help him avoid that mistake in the future? how could bill have realized that its wrong?

this is the link of the worksheet its on page 3 (HW2-3) question C.
http://panda.unm.edu/Courses/Saul/Physics1/Tutorials/02_V_and_A_Graph_Tutorial_HW.pdf [Broken]

Last edited by a moderator: May 5, 2017
2. Sep 15, 2011

### Gordanier

I'd suggest to Bill to use a better graphing program

Seriously though :P What is the graph representing?

3. Sep 15, 2011

### Arlene87

lol sorry it didnt work out to well.. its suppose to be 2 triangles. i posted the link on the post so you can see the actual problem its on page 3.

4. Sep 15, 2011

### Gordanier

Ok that is much better :) Completely different than what I had originally imagined it, lol.

Ok, so the issue is, the ball is accelerating as it rolls down ramp A, once it reaches the bottom and begins horizontally rolling, its velocity is the same, not 0. Meaning the time between ramp A and ramp B, the velocity doesn't change, but the velocity isn't 0 either, or it would never get to ramp B. So the flat horizontal line should not be along the x axis, but rather at the peak velocity, virtually connecting your two slopped lines.

If you knew that and just looking for the answers of why bill made this mistake, there are many, and all just as relevent since no other information is given. But you could theorize that he assumed he confused the acceleration and velocity graphs, so since the ball is moving at a constant velocity, its acceleration is 0. I would advise Bill to better understand the differences between acceleration and velocity? Or maybe tell him to take more time in answering questions and think it through, since he got the above two graphs correct?

Opinion questions are the best, you could say it was because he was on crack and advise him to quit drugs.

5. Sep 15, 2011

### Arlene87

you are the best! THANKS!! LOL