17. How long does it take a giraffe running at a speed of 33 m/s to run 200 meters !

Hydrogen and helium are both members of?

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.

Use 4 to 5 complete sentences, explain the concepts of beats and how beats are produces.