What colour light does a violet book reflect

Aneutron and a proton combine to form a nucleus. why does the mass of the nucleus differ from the sum of the masses of the individual nucleons?

An inclined plane wrapped around a metal shaft is a a. lever b. screw c. pulley d. wedge

An equinox occurs when a. neither end of earth's axis is tilted toward or away from the sun. b. the north end of earth's axis is tilted away from the sun. c. the north end of earth's axis is tilted toward the sun. d. earth's axis is parallel to the sun's rays. select the best answer from the choices provided a b c d