Question

A 20.0 kg cart is moving with a velocity of 7.30 m/s down a level hallway. A constant force of -11.0 N acts on the cart and its velocity becomes 3.50 m/s. a) What is the change in kinetic energy of the cart? b) How much work was done on the cart? c) How far did the cart move while the force acted?

My thoughts: KE = 1/2mv^2. The mass would be 20.0 kg. How would you find the change in kinetic energy?

Answer 1

a) (1/2) M [V2^2 - V1^2]
b) Negative work is done slowing it down. Same result as (a), if there was no friction. If there was friction, you have to know how far it moved to compute the work done.
c) Assuming no friction,
Work done = (force)*(distance) = kinetic energy change
Solve for the distance