A pulley system used to lift car tires has a mechanical advantage of 8.1. If you pull on the pulley with a force of 540 N, how much force does the pulley
exert on the tire?
A. 1205 N
B. 4374 N
C. 66.7 N
D. 5110 N

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?