How can the density of an object be determined

Apossible explanation for a set of facts that can be tested by further investigation is called

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 ?

Which articulations allow for greatest range of motion?