Question

A body of mass 10 kg undergoes a change in speed from 10 m/s to 10 cm/s. Then the momentum of the body -

1. increases by 99 kgms^-1
2. decreases by 99 kgms-1
3. increases by 90 kgms-1
4. decreases by 90 kgms-1

Answer 1

Correct Answer - Option 2 : decreases by 99 kgms-1

The correct answer is option 2) i.e. decreases by 99 kgms-1

CONCEPT:

• Momentum: Momentum is the impact due to a moving object of mass m and velocity v.

The momentum (p) of an object is expressed as:

⇒ p = mv

​CALCULATION:

Initial speed of the body, u = 10 m/s

Final speed of the body, v = 10 cm/s = 0.1 m/s

Initial momentum, p₁ = mu = 10 × 10 = 100 kgms^-1

Final momentum, p2 = mv = 10 × 0.1 = 1 kgms-1

Change in momentum = p₂ - p₁ = 1 - 100 = -99 kgms^-1

Therefore, the momentum decreases by 99 kgms-1