What is considered one of the most important innovations of the bicycle? A. the development of the chain-driven rear-wheel
B. the invention of pedals
C. two wheels that are the same size
D. brakes help mee please

An electric current in a wire will push or pull on a permanent magnet. which statement best explains how an electric current creates an electromagnetic force on another magnet?

Ammonia enters the expansion valve of a refrigeration system at a pressure of 10 bar and a temperature of 18oc and exits at 6.0 bar. the refrigerant undergoes a throttling process. determine the temperature, in oc, and the quality of the refrigerant at the exit of the expansion valve.

The force needed to overcome static friction is usually less than that needed to overcome kinetic friction. true or false?