Copernicus postulated that earth moves around the sun (rather than the other way around) but he was troubled about the idea. What concepts of mechanics was he missing that would have eased his doubts?

If there's a small amount of friction between two surfaces, the result could be select all that applya. no movement b. heatc. a little bit of movementd. sliding around

Anonzero net force acts on a particle and does work. which one of the following statements is true? the kinetic energy of the particle changes, but the speed of the particle does not change. the kinetic energy of the particle does not change, but the speed of the particle does change. the kinetic energy of the particle changes, but the velocity of the particle does not change. the kinetic energy and the speed of the particle change, but the velocity of the particle does not change. the kinetic energy, speed, and velocity of the particle change.

The gun from the crime scene shows tool marks where the serial numbers are ground off. there are also tool marks on the bullets left behind. what information can the tool marks on the bullets and gun provide about the crime? what type of evidence does this information provide, individual or class?