A freight car of mass 1800 kg is timed at 4.2 m/s just after it runs into a spring-loaded bumper at the end of the track. The bumper consists of an 800 kg mass that the car runs into, and a pair of large springs. The car travels 2.4 m before coming to rest. a. Using an appropriate conservation law, find the speed of the freight car before it struck the bumper. b. Find the time taken for the car to be brought to rest.

a)Find an expression for the bullet's initial speed v_B in terms of m, M, k, and d. Express your answer in terms of the variables m M k d b)What was the speed of a 1.8 g bullet if the block's mass is 1.1 kg and if the spring, with k = 37 N/m , was compressed by 16 cm? Express your answer in meters per second. c)What percentage of the bullet's energy is "lost"? Express your answer in percent to four significant figures.

24.  The kinetic energy of an object is 200 Joules while its' momentum is 8 kg m/s. What is the speed of this object?     A. 25 m/s   B. need to know the mass   C. 1600 m/s   D. 50 m/s   E. 80 m/s

Car Striking a A 1000 kg vehicle traveling at 30 m/s smashes into a tree and comes to rest as shown. The front of the car is compressed a distance of 0.3 m. What is the time interval, At of the collision? (Assume the net force exerted by tree on the car is constant over time interval) A. 1.00 s B. 0.20 s C. 0.10 s D. 0.02 s E. 0.01 s

A 0.12 kg egg is dropped from a height of 2m and falls into an egg catcher.a. How fast is the egg traveling when it falls into the catcher from the height of 2m?b. If the catcher takes 0.2 seconds to bring the egg to a stop, what average force acts on the egg during the catch?

Match the following behavior with the physics concept it illustrates          -           A.           B.           C.           D.           E.       Acceleration of a rocket at launch          -           A.           B.           C.           D.           E.       Rebound of a basketball off the backboard          -           A.           B.           C.           D.           E.       Occupant protection in an automobile crash          -           A.           B.           C.           D.           E.       Proportional to velocity          -           A.           B.           C.           D.           E.       Proportional to square of velocity A. Conservation of momentum and thrust B. Elastic collision C. Inelastic collision D. Energy E. Momentum

2. A 20.0 kg object is dropped off of a 30.0 m cliff. How fast is the object going when it hits theground?