How much heat is needed to raise the temperature of 1 kg of brass by 20 ° C
(need an explanation)

The of a machine determines its "usefulness." a. input force b. output force c. mechanical advantage

Arotating space station is said to create “artificial gravity”—a loosely-defined term used for an acceleration that would be crudely similar to gravity. the outer wall of the rotating space station would become a floor for the astronauts, and centripetal acceleration supplied by the floor would allow astronauts to exercise and maintain muscle and bone strength more naturally than in non-rotating space environments. if the space station is 200 m in diameter, what angular velocity would produce an “artificial gravity” of 9.80 m/s^{2} 2 at the rim?

Determine the age of a fossil if it had only one eighth of its original carbon-14 content remaining?