Question

It takes 300 newtons of force and a distance of 20 meters for a moving cart to come to a stop. How much kinetic energy did this cart have?

Answer 1

As we know from work energy theorem

Work done by all the forces is change in kinetic energy of the system

here we know that finally it stops so final kinetic energy of the cart here is ZERO

while we need to find the initial kinetic energy of the cart which is equal to the work done

so here we can say

$W = KE$

also we know that work done by the force is given by

$W = F.d$

here we have

F = 300 N

d = 20 m

$W = 300 \times 20$

$W = 6000 J$

so kinetic energy of the cart will be 6000 J