a string of mass 0.50 kg and a length 3.0 meters is clamped on both ends. if the tension in the string is 25 newtons what are the lowest 3 natural frequencies

Arailroad car collides with and sticks to an identical railroad car that is initially at rest. after the collision, the total kinetic energy of the two cars is a) the same as before. b) half as much as before. c) one third as much as before. d) one fourth as much as before. e) twice as much as before.