# Homework Help: One Dimensional Kinematics Question (Simple)

1. Aug 29, 2010

### PanChan89

1. The problem statement, all variables and given/known data
1. A ball is rolling along the x-axis. At t=2s it is located at x =6m, at t=4s it is at x=16m, and at t=8s it is at x=48 m. Assume Constant acceleration.

a) Find its displacement from 2s to 4s. -- I put 10m
b) find its average velocity from 2s to 4s.---- 5 m/s
c) find its average velocity from 4s to 8s. ----8m/s
d) what is t when the objects velocity is equal to its average velocity during the first time interval. --- t= 3 seconds.

and a fill in chart...

Tj is the time at which the jth video frame is captured. The position xj is the position of the steel ball in the jth frame (the data is taken at 30 times per second).

j tj(s) xj (m)
1 0.0333 s 0.0250 m
2 0.0667 s 0.0820 m
3 0.1000 s 0.130 m
4 Unknown 0.164 m
5 Unknown 0.190 m

I need help filling out the Tj's for J4 and J5. I have no idea where to start.

2. Relevant equations

3. The attempt at a solution
If someone can also explain how to do D in the first portion I would appreciate it, I'm mainly having problems with the chart.

Last edited by a moderator: Aug 29, 2010
2. Aug 29, 2010

### Redbelly98

Staff Emeritus
Welcome to Physics Forums.
You're answer for (d) is correct.
As for the chart, there is a kinematics equation (one of the equations dealing with constant acceleration motion) which gives the displacement as a function of time. That will be useful here.