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.
Mass of the dumbbell, m = 10 kg
Distance, s = 80 cm = 80 / 100 = 0.8 m
Acceleration, a = 10 m/s2
Initial velocity of the dumbbell, u = 0
Final velocity of the dumbbell = v
Using the third equation of motion:
v2 = u2 + 2as
v2 = 0 + 2 (10) 0.8
v = 4 m/s
Hence, the momentum with which the dumbbell hits the floor is
= mv = 10 × 4 = 40 kg m/s
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