Is the wavelength of the radiation that excites a fluorescent material greater than, less than,
or equal to the wavelength of the radiation that the
material emits? explain

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 ?