When a source of sound moves, the frequency ahead of the source is higher than the frequency behind it.  This change in frequency is called

The speed of sound

Archimedes’ principle states that

The emission of energy from the surface of all bodies is

The transfer of heat by the movement of a heated fluid is

The vertical flight of a helicopter is controlled by

If the pressure of a dry gas is reduced by one third, the volume will

A weight of sixty pounds is supported by pulleys which are supported by four ropes.  How much force must be applied to move the weight?

In a hovering helicopter equipped with a tail rotor, directional control is maintained by

Pascal’s Law states that