A 5.08×104 kgkg railroad car moves on frictionless horizontal rails until it hits a horizontal spring stopper with a force constant of 4.09×105 N/mN/m . When the railroad car comes to a complete stop, the compression of the spring stopper is 30 cmcm . How fast was the railroad car initially?

A ball of mass 160 g is dropped from a height 1.5 m and bounces off the floor with a velocity 3.0 m/s [Up]. If the average Force on the ball from the floor is 15 N [up], for how long is the ball in contact with the floor in milliseconds?

Gayle runs at a speed of 4.35 m/s and dives on a sled, initially at rest on the top of a frictionless snow covered hill. After she has descended a vertical distance of 5.00 m, her brother, who is initially at rest, hops on her back and together they continue down the hill. What is their speed at the bottom of the hill if the total vertical drop is 18.5 m? Gayle's mass is 50.0 kg, the sled has a mass of 5.00 kg and her brother has a mass of 30.0 kg. m/s

Batman observes a robber driving away from a jewelry store with a bag full of loot.  He takes off in his batmobile and catches up with the robber 14m away from where his batmobile was idling at rest.  When he was catching up with the robber his batmobile (which has a mass of 800kg with Batman inside) experiences a constant net force of 10,000N from his tires on the road. How long did it take for Batman to catch the robber? ROUND TO THE NEAREST TENTH! USE THE ROUNDED VALUE FOR THE REST OF THE PROBLEM.                              =  s When he catches up, Batman slams into the robber who was driving a 560kg car at a speed of 8m/s.  Unfortunately the two vehicles get tangled up and begin to slide off together.  (YOU CAN IGNORE FRICTION DURING THE COLLISION ONLY).  Remember both cars are driving in the same direction. How fast were the two vehicles going the instant after they collided? ROUND TO THE NEAREST HUNDREDTH! USE THE ROUNDED VALUE FOR THE REST OF THE PROBLEM. =  m/s What…