A pitching machine is programmed to pitch baseballs horizontally at a speed of 87 mph . The machine is mounted on a truck and aimed backward. As the truck drives away from a man at a speed of 65 mph, the machine shoots a ball towards him.
For each of the object pairings listed below, determine the correct relative speed.

a - The speed of the pitching machine relative to the truck

b - the speed of the pitched ball relative to the truck

c - the speed of the pitching machine relative to him

d - the speed of the pitched ball relative to him

To create electromagnetic induction, which of the following has to move? a. a wire b. a magnet c. a transformer d. either a or b

Acoal-fired plant generates 600 mw of electric power. the plant uses 4.8 x 10^6 kg of coal each day, and the heat of combustion of coal is 3.3x 10^7 j/kg. the steam that drives the turbines is at a temperature of 300° c, and the exhaust water is at 37° c. (a) what is the overall efficiency of the plant for generating electric power? (b) how much thermal energy is exhausted each day? (c) what is the change in entropy of the universe for this heat engine? (d) using the same heat reservoirs, what is the maximum possible (carnot) efficiency for a heat engine?

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?