Question

A ball of mass 150 g moving with an acceleration 20 m/s² is hit by a force which acts on it for 0·1 s. The impulse is
1. 1·2 N s
2. 0·3 N s
3. 0·1 N s
4. 0·5 N s

Answer 1

Correct Answer - Option 2 : 0·3 N s

Concept:

Impulse and Momentum

• Momentum: The product of the mass and velocity of an object in motion is called momentum.
  • It is a vector quantity.
  • The unit of momentum is kg m s ^-1. 
• Impulse: The change of momentum is called impulse. 
  • It has the same unit as momentum. 
• The rate of change of momentum is called Force by the second law of motion. 

\(F = \frac{Δ P}{t}\)

Δ P is a change in momentum or impulse, t is time.

• Impulse can also be defined as the product of force and time. 

Δ P = F × t

• The Force is also defined as the product of mass and acceleration. 

Calculation:

Mass of ball m = 150 g = 0.15 kg

time t = 0.1 s

Acceleration a = 20 m /s ² 

Force = ma = 0.15 kg × 20 m /s ² = 3 N

Impulse = Force × time =  3 N × 0.1s = 0.3 N s

So, the correct option is 0·3 N s.