A 0.5 kg ball is at rest at the top of a 20 meter tall hill. A) What is the ball's kinetic energy?
B) What is the ball's mechanical energy

Acatapult is tested by roman legionnaires. they tabulate the results in a papyrus and 2000 years later the archaeological team reads (distances translated into modern units): range = 0.4 km; angle of launch = π/5 rad; landing height = launch height. what is the initial velocity of launch of the boulders if air resistance is negligible?

Idon’t quite understand this problem

If an athlete runs once around a track, back to the starting line, her average velocity is zero. true or false?