The force that contributed to the formation of planets, determines the motion of bodies in the solar system, and pulls objects to the center of Earth is called

Ahollow metal sphere has 6 cm and 11 cm inner and outer radii, respectively. the surface charge density on the inside surface is −100nc/m2. the surface charge density on the exterior surface is:

Consider a system to be two train cars traveling toward each other. what is the total momentum of the system before the train cars collide?   kg • what must the total momentum of the system be after the train cars collide?   kg •  

Why is the energy that results from a roller coaster's position at the top of a hill referred to as potential energy?