Determining impulse on baseball from bat given velocity change

[hcps-chent1]

Homework Statement

A(n) 0.182 kg baseball is thrown with a speed of 15.3 m/s. It is hit straight back at the
pitcher with a final speed of 10.4 m/s. What is the magnitude of the impulse delivered to the ball?

Homework Equations

impulse=mass*change of velocity

The Attempt at a Solution

.182*-4.9(change in velocity)=-.8918 answer is wrong is it the sign

 

[Filip Larsen]

It is a sign problem, yes. Select a direction and write speeds in that direction as positive numbers and speeds in the opposite direction as negative numbers and try again (hint: the change in velocity is not 4.9 m/s but 25.7 m/s).