A ball is dropped from a height of 10m. If the energy of the ball reduces by 40% after striking the ground, how much high can the ball bounce back ?

(g 10ms2

on reaching the ground the energy of the object = the energy at the top **[law of conservation of mass]**

energy at the top = potential energy = mgh

= m*10*10 = 100x joule **[ let mass be x]**

loss of energy = 40% of 100x J

energy left = 60% of 100x

= 60/100 * 100x = 60x

now the energy of the object on reaching the top again will be equal to that at the surface = 60x

bt height will differ

E_{p = }mgh = x*10*h

60x = 10xh

60x / 10x = h

h = 6 meter

:. the ball bounce back to 6m...

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