One astronomer believes that the density of the universe remains constant. one physicist believes that the density of the universe changes over a period of time. which of these statements best explains why the astronomer and physicist have different views on the density of the universe? most data on density of the universe are inaccurate. scientists provide different theories to strengthen science. scientists having different interests arrive at different conclusions. most experiments on density of the universe cannot be repeated.

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.

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me