A ball of mass 2kg dropped from a height H above a horizontal surface rebounds to a height h after one bounce. The graph that relates H to h is shown in figure. If the ball was dropped from an initial height of 81 m and made ten bounces, the kinetic energy of the ball immediately after the second impact with the surface was

Options

A. 320J
B. 480J
C. 640J
D. Can't be determined

Answer

(A)

Explanation

From graph `e = sqrt(h/H) = sqrt(40/90) = 2/3`
Kinetic energy of the ball just after second bounce
`=1/2m(e^(2)u)^(2) = 1/2me^(4)u^(2) = e^(4)(mgH) = (2/3^(4))(2)(10)(81) = 320J`