A hot air balloon is hovering at a height of 52 m above the ground. A penny is dropped from the balloon. Assume no air resistance.
(a) How long does it take the penny to hit the ground? [ans: 3.3 s]
(b) What is the final velocity of the penny just before it hits the ground?

What was the purpose of the apollo program? to put a man in orbit to launch a spy satellite to launch a space station to put man on the moon

What energy transformations occur each time the skateboarder rolls up the ramp?

Conventional hot-water heaters consist of a tank of water maintained at a fixed temperature. the hot water is to be used when needed. the drawback is that energy is wasted because the tank loses heat when it is not in use, and you can run out of hot water if you use too much. some utility companies are encouraging the use of on-demand water heaters (also known as flash heaters), which consist of heating units to heat the water as you use it. no water tank is involved, so no heat is wasted. a typical household shower flow rate is 2.50 gal/min (9.46 l/min ) with the tap water being heated from 51.0 ˚f (10.6 ˚c) to 120 ˚f (48.9 ˚c) by the on-demand heater. what rate of heat input (either electrical of from gas) is required to operate such a unit, assuming that all the heat goes into the water?