A 40 kg child is on a swing. When the child is 1.5 m above the ground, she is moving at 2m/s. What is the child's potential energy?

A500g object falls off a cliff and losers 100 j from its gravitational potential energy store. if the gravitational field strength g=9.8n/kg, how high is the cliff?

The percent efficiency of a machine can never be 100% (or greater), because in the real world some energy is always converted into a. heat b. work c. input force d. output force

How does the kinetic energy of a charge change as the charge moves under the effect of an electric field from higher potential to lower potential? a.the kinetic energy increases.b.the kinetic energy decreases.c.the kinetic energy remains the same.d.the kinetic energy is always zero.