An empty train car moving at 21 m/s collides with a loaded train car initially at rest that has twice the mass of the empty car. The two cars couple together. a) What is the final velocity of the cars after the collision? 7 m/s
b) Is kinetic energy conserved in this collision? If so, how do you know? If not, why is there a difference?

You have been called to testify as an expert witness in a trial involving a head-on collision. car a weighs 1515 lb and was traveling eastward. car b weighs 1125 lb and was traveling westward at 44.0 mph. the cars locked bumpers and slid eastward with their wheels locked for 22.5 ft before stopping. you have measured the coefficient of kinetic friction between the tires and the pavement to be 0.750 . how fast (in miles per hour) was car a traveling just before the collision? (this problem uses english units because they would be used in a u.s. legal proceeding.)

What is the length x of the side of the triangle below? (hint: use the cosine function)

You win the lottery and decide to impress your friends by exhibiting a million-dollar cube of gold. at the time, gold is selling for $ 426.60 per troy ounce, and 1.0000 troy ounce equals 31.1035 g. -how tall would your million-dollar cube be? en cm