Q18 of 31 Page 128

How much momentum will a dumb-bell of mass 10 kg transfer to the floor if it falls from a height of 80 cm? Take its downward acceleration to be 10 m s-2.

Firstly, we will calculate the final velocity:

Given,


Initial velocity, u = 0 (As it falls from rest)


Final velocity, v =?


Acceleration, a = 10 ms2


And, Distance, s = 80 cm


= m


= 0.8 m


We know that,


v2 = u2 + 2as


v2 = (0)2 + 2 × 10 × 0.8


v2 = 16


v =


= 4 m/s


Momentum = Mass × Velocity


= 10 ×4


= 40 kg m/s


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