Match these early theories of the sun. combustion theory sun's energy caused by hydrogen burning radioactive-substance theory sun's energy caused by objects striking the sun contraction theory sun's energy caused by gases on the sun compressing meteor-impact theory sun's energy caused by radioactive decay

when two balls of the different masses are dropped from equal height, they reach the ground at the same time .this is because they experience the same acceleration.

the acceleration is independent of mass.

thus when they are dropped they will always maintain the same velocity and travel the same distance (neglect air resistance of course) at the same time.

amplitude

hope this

3. dark matter

empty space could also be a simple vacuum