A skateboarder pushes the ground with one foot, and moves forward. Which statement BEST explains his motion?
The mass of the skateboard decreased causing acceleration to move him forward.
The unbalanced force exerted by the skateboarder’s foot caused him to move forward.
The mass of the student and skateboard increased causing acceleration to move him forward.
The balanced forces on the skateboard allowed it to change his motion and move him forward.

D because to ride a skateboard you need balance to move you forward or you will fall

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.