Over the course of 30 seconds, 3 waves hit the shore. What is the period of the waves?

Alead ball is dropped into a lake from a diving board 5m above the water . it hits the water with a certain velocity and then sink with constant velocity in bottom . it reaches the bottom 5 second after it is dropped if g= 10m/s2 . find depth of the lake and average velocity of the ball ?

If jerome is swinging on a rope and transferring energy from gravitational potential energy to kinetic energy, is being done.

What is the relationship between wavelength of light and the quantity of energy per photon?