A 1 kg rock is dropped from a height of 6 m. What is its potential energy when it hits the ground? What is the kinetic energy of the rock in question 15 when it just hits the ground?

Consider a mass m=81.6 kg sliding on a frictionless surface as shown in the figure below. It begins with a speed of vi = 1.81 m/s at a height of yi = 21.4 m above the ground. It then travels down one hill and up the next until it momentarily comes to rest with a speed vi = 0.  a) What is its kinetic energy of the mass at the start? b) What is its gravitational potential energy of the mass at the start?

A brick lies perilously close to the edge of the flat roof of a building. The roof edge is 50 ft above street level, and the brick has 260.0 J of potential energy with respect to street level. Someone edges the brick off the roof, and it begins to fall. What is the brick’s kinetic energy when it is 35 ft above street level? What is the brick’s kinetic energy the instant before it hits the street surface?

A 20 N ball is thrown upward with an initial  kinetic energy of 100 J. How much gravitational potential energy will the ball have when it reaches the top of its path?   2000 J 100 J 50 J 5 J   Which is correct?