What is the velocity of a 30-kg box with a kinetic energy of 6,000 j? 64 m/s
6.0 m/s
18 m/s
20 m/s
36 m/s

20 m/s

Explanation: To solve this problem we have to consider the expression of the kinetic energy given by:

Ekinetic=(1/2)*(m*v^2)

then E=0.5*30Kg*(20 m/s)^2=15*400=6000J

The GPE at the start will change to KE as it rolls down the first hill. Conservation of energy means that KE will change back to GPE, but even if no energy transfer takes place to the surroundings, the ball will not reach the top of the next hill. It is higher than the first so it will not have enough energy to get there.