Which of the following is a contact force?
a. air resistance
b. magnetic force
c. gravity
d. electrical force

Air resistance is a contact force as the air comes in direct contact with the object and pushes against it. Magnetic force - you can attract a magnet without touching it. Gravity, works on you when you are not in contact with the earth, pulling you down. Electrical force, between 2 electrons when not in contact.

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.