What law states that when matter undergoes a physical or chemical change, no atoms are created or destroyed?

Most short-period comets do not have randomly oriented orbits because

What is friction? how does it affect the motion of an object?

Four objects each with charge +2.0×10−7c are located at the corners of a square whose sides are 2.0 m long. part a what quantities can be determined using this information? check all that apply. the electric force on a charged object placed at the center of the square. the mass of each object. the total electric potential energy of the system consisting of the four charged objects. part b find the electric force on a charged object placed at the center of the square.