Question

A particle of mass 2 kg is dropped from a height of
20m and rises to a height of 5m. Calculate the
change in momentum between before and after
hitting the ground
(1) 30 kg m/s
(2) Zero
(3) 10 kg m/s
(4) 60 kg m/s​

Answer 1

Answer:

4-60 kg m/s

Explanation:

Velocity=(2×height /g) ^1/2

where, g=acceleration due to gravity=10

Initial velocity=(2×initial height /g) ^1/2

=20m/s

Final velocity=(2×final height /g) ^1/2

- 10m/s('-' is used because direction is opposite to initial direction)

Change in momentum=mass×change in velocity=2×[20-(-10)]=60 kg m/s