Question

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.

Answer 1

Mass of the bell (m) = 10kg

Initial velocity (u) = 0

And let the final velocity = v

Distance (s) = 80cm

= 0.8m

Acceleration (a) = 10ms²

Therefore, according to the third equation of motion

v² = u² + 2as 

v² = 0 + 2 × 10 × 0.8

v² = 16

v = 4m/s

Hence, momentum = mv

= 10 × 4

= 40 kgm/s

Since the bell's momentum just before touching the floor is 40 kgm/s, the momentum transferred by the bell to the floor will be 40 kgm/s.