3. Which of the following describes why fossil fuels are nonrenewable? A) It is very difficult to drill for fossil fuels, and we don't have the resources to do it.
B) Fossil fuels formed from plants and animals that lived many, many years ago.
C) Fossil fuels are destroyed when we use them.

The energy equivalent of the rest mass of an electron is

Engines for propeller-driven aircraft are limited in their maximum rotational speed by the fact that the tip speed of the propeller must not approach the speed of sound in air (mach i). taking 6 ft as a typical diameter for a propeller of a light airplane and 1100 fils as the speed of sound, find the upper limit on the rpm (revolutions per minute) of the propeller shaft.

An object is kept at 45 m high and how much time will it take to reach the ground