Work is done when a force a. is exerted while pulling a wagon up a hill b. acts vertically on a cart that can only move horizontally c. is exerted by one team in a tug of war when there is no movement d. of gravitaional attarction acts on a person stabnding on the surface of the earth

The answer is going to be A.

1) when you rub your hands together quickly, the kinetic energy is converted to mechanical energy.2) thermal energy from the sun travels to earth as infrared waves.3) energy is transferred through the matter of space by electromagnetic waves. 4) when a match is burned, chemical potential energy is converted to thermal and radiant energy. 5) seismicwaves are caused by back and forth movement , or vibration, of an object. 6) mechanicalenergy in an engine changes thermal energy into kinetic energy to make a car move.

The charge of an ion with 55 protons and 52 electrons is +3. the reason is because protons are positive, and there are three more than the amount of negative electrons.