A rubber ball is dropped from a height of 5 m on a planet where the acceleration due to gravity is not known, On bouncing it rises to 1 .8 m. The ball loses its velocity on bouncing by a factor of

When the ball strikes the surface of planet, the potential energy is changed into kinetic energy.Thus12mv2=mghor v2 =2gh=2 x g x 5=10gAfter rebounce, v2 = u2 - 2 g hor u2 =v2 + 2gh∴u2=0+2×g×1⋅8=3⋅6gNow v2u2=10g3⋅6g=10036 or vu=106=53or u=35vThus the ball loses it velocity by a factor of1−35=25