What kind of wave supports that the universe is expanding?

In a bumper car arena, two cars of equal mass are heading straight toward each other. the orange one is traveling at a speed of 5 meters per second. the green one is traveling at a speed of 2 meters per second. which of the forces most affects the motion of the bumper cars after they collide? a) gravity b) friction c) the other car d) wind resistance

Arock collection comes from which part of earth?

If a balloon is taken outside on a very cold day, what will occur?