Ignoring air resistance, use an energy argument to find the speed of a ball when it hits the ground if it is dropped from 50m, where m is the mass of the ball.
Original energy: GPE=509.81m KE=0 Final energy: GPE=0 KE=(1/2)mv2 Therefore (1/2)mv2 = 50m9.81 . The m cancels and simplifying the equation we are left with v2 = 5029.81, therefore v = 31 ms-1
