1 Work Power Energy
A ball is thrown vertically downwards from a height of 20 m with an initial velocity u0. It collides with the ground, loses 50 percent of its energy in collision and rebounds to the same height. The initial velocity u0 is : (Take g = 10 ms-2)
1) 10 ms-1 2) 14 ms-1 3) 20 ms-1 4) 28 ms-1
SOLUTION:− Final potential energy after rebound = mgh = m×10×20=200m Final PE. = 50%(Initial K.E+ PE) 800 = v2 + 2× 10×20 v2 = 400 v= 20 m/s
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