As part of a safety investigation, two 1600 kg cars traveling at 21 m/s are crashed into different barriers.

a) find the average force exerted on the car that hits a line of water barrels and takes 1.8 s to stop.
b) find the average force exerted on the car that hits a concrete barrier and takes 0.14 s to stop.

The coefficient of friction is a number that represents the resistance to sliding between two in contact with one another.

The sun’s mass is 2.0×10^ 30 kg, its radius is 7.0×10 5 km, and it has a rotational period of approximately 28 days. if the sun should collapse into a white dwarf of radius 3.5×10 3 km, what would its period be if no mass were ejected and a sphere of uniform density can model the sun both before and after?

The air in an automobile tire with a volume of 2.60 ft3 is at 70°f and 21 psig. determine the amount of air that must be added to raise the pressure to the recommended value of 30 psig. assume the atmospheric pressure to be 14.6 psia and the temperature and the volume to remain constant. the gas constant of air is ru = 53.34ft⋅lbflbm⋅r(1 psia144 lbf/ft2) = 0.3704 psia⋅ft3lbm⋅r the amount of air that must be added to raise the pressure is lbm