Correct Answer - 40 kg
Mass of the dumbbell, m = 10 kg
Distance covered by the dumbbell, s = 80 cm = 0.8 m
Acceleration in the downward direction, `a = 10 m//s^(2) `
Initial velocity of the dumbbell, u = 0
Final velocity of the dumbbell (when it was about to hit the floor) = v
According to the third equation of motion:
` v^(2)= u^(2) + 2as`
` v^(2)= 0 + 2 (10) 0.8 `
v= 4 m/s
Hence, the momentum with which the dumbbell hits the floor is
= mv ` = 10 xx 4 kg ms^(-1)`
` = 40 kg ms^(-1)`