Momentum of the rock = 85.7 Kgm/s
Step-by-step explanation:
Given
Rock weight = 5 kg
height of a cliff = 15 m
find Momentum =?
Momentum = mass × velocity
we don't have velocity here so let's find the velocity v
Potential energy of the rock will be = mgh
P.E. = mgh
⇒ 5 × 9.8 × 15
⇒ 735 J
The Kinetic energy before a moment of touching the ground will be = maximum potential energy = 735 J ⇒ Going by the law of conservation law.
K.E. = 1/2 m × v²
735 = 1/2 × 5 × v²
v² = 294
v = 17.14 m/s
Now get on to the momentum
Momentum = m × v
Momentum = 5 × 17.14
Momentum = 85.7 Kgm/s
The Momentum of the rock as it strikes ground will be 85.7 Kgm/s.