# Homework Help: Incline Plane ball rolling up

1. Dec 14, 2008

### charan1

1. The problem statement, all variables and given/known data

A ball rolls up a straight incline. The dots in the diagram represent the position of the ball every 4 seconds.
(The fourth dot is not intended to represent the turnaround point; the ball might still be on the way up at that
point.) The instantaneous velocities at the second and third dots are as given in the diagram.

a. Determine the velocities at the locations of the first and fourth dots and label them on the diagram. (2 points)

b. Determine how far the ball travels between the second and third dots. (3 points)

c. Determine the total time it takes the ball to roll up the incline, from the bottom to the turnaround point.

3. The attempt at a solution

Part A:
Equations:
Vf=Vi+a(delta T)
aavg=D=(delta V)/(delta T)

VDot 2=7m/s
VDot 3=5m/s

aavg=(5m/s-7m/s)/(8s-4s)=-.5m/s2

VDot 2=VDot 1+(-.5m/s/s)(4s-0s)
VDot 1=9m/s

VDot 4=VDot 3+(-.5m/s/s)(12s-8s)
VDot 4=3m/s

Part B:

Equation:
vf2=vi2+2a(delta x)

52=72+2(-.5m/s/s)(delta x)
(Delta x)=24m

Part C:

Equation:
vf=vi+a(delta T)

vf=0m/s
vi=9m/s
a=-.5m/s/s
(delta T)=?

0m/s=(9m/s)+(-.5m/s/s)(delta T)

(delta T)=18s

2. Dec 15, 2008

### LowlyPion

Without seeing your drawing, nothing stands out as wrong that I notice.

3. Dec 15, 2008

Thank you!