Being sold at an army surplus store is a pen gun. The pen gun fires a .22 caliber cartridge with a short barrel that has no rifling, so it must be shot at very close range such as 2ft or 3ft to do damage. What is the pen gun’s diameter in inches?

What is relative velocity? in which condition is relative velocity known by adding the velocity of the first body and that of the second body

Explain earth's motion, using the terms "precession" and "rotation" in your answer.

Air is to be preheated by hot exhaust gases in a cross-flow heat exchanger before it enters the furnace. air enters the heat exchanger at 95 kpa and 20°c at a rate of 0.6 m^3/s. the combustion gases (cp = 1.10 kj/kg°c) enter at 160°c at a rate of 0.95 kg/s and leave at 95°c. determine the rate of heat transfer to the air and its outlet temperature.