If im pushing on a wall what are the action and reaction force?

According to an observer on earth, planet x is stationary. maria and samir depart earth on their spaceships at the same time, each flying at 0.5c. maria flies toward planet x and samir flies in the opposite direction. according to maria, her voyage to planet x takes 9 years. how many years does maria's voyage take according to samir?

A51 kg woman skis down a hill and her kinetic energy is 9.96e4 j. what is her speed?

What happens during the fall in september