-ASTRONOMY CLASS- Lanes of young stars, gas, and dust that wind outward from the central region of spiral galaxies can be identified as

Spiral arms
Quasars
Local groups
Superclusters

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.