They make your muscles stronger and keep the bones, heart, and lungs in good condition. It implies that you have less chance of blood clotting and heart attack. one can balance his mood well and is likely to experience less stress in life.It also helps us to practice discipline.
The energy carried by the incident light is

where h is the Planck constant and f is the frequency of the light. The threshold frequency is the frequency that corresponds to the minimum energy needed to eject the electrons from the metal, so if we substitute the threshold frequency in the formula, we get the minimum energy the light must have to eject the electrons:
it will move the object if you apply force, because of that it will stay the same with newton's law.
That's true, and there are also other mechanisms that can also create floods.