Why might coal be considered a more efficient source of energy than biomass? (1) Coal is a more concentrated energy source (2) Coal is nonpolluting. (3) Biomass grows very slowly (4) Biomass is only available in windy areas. I

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.