Determine the work done on the object during each of the five intervals using velocity-versus-time graph?

Question

The figure http://session.masteringphysics.com/problemAsset/1073718/4/11.EX13.jpg is the velocity-versus-time graph for a 2.0 kg object moving along the x-axis.

Determine the work done on the object during each of the five intervals AB, BC, CD, DE, and EF.

Express your answers using two significant figures. Enter your answers numerically separated by commas.

Answer 1

0,0,-9.6,9.6,-7.2 all in Joules.

Answer 2

One way to find work is to do the usual;

Work=forceXdistance

The other is work is the change in kinetic energy;

Work = 1/2 m v1^2 - 1/2  v2^2

For ab it is 1/2 2 (2^2-(-2^2))=0

When I go back and forth between the graph to get the other velocities I keep wiping what I wrote out. Do the rest of the calculations yourself.

And check out the wikipedia source below to see what I mean about work being a change in kinetic energy.