What si unit is used to measure mechanical energy

Students design a model roller-coaster track. they place a rubber ball at the highest point on the track and let it go. the ball rolls along the track pulled only by the force of gravity. eventually, it comes to a stop. which change to the design will result in the ball moving the greatest distance?

What are the north and south poles of a solenoid change with?

How does the entropy of steam compare to the entropy of ice?