A cricket ball of mass 500 g is moving with speed of `36 k m h^(-1)` . It is reflected back with the same speed . The impulse (in kg ` m s^(-1)` ) applied on it is ______

Explanation

To solve the problem, we need to calculate the impulse applied to a cricket ball of mass 500 g that is moving at a speed of 36 km/h and is reflected back with the same speed.

### Step-by-Step Solution:

1. **Convert Mass from grams to kilograms**:
\[ \text{Mass (m)} = 500 \, \text{g} = \frac{500}{1000} \, \text{kg} = 0.5 \, \text{kg} \]

2. **Convert Speed from km/h to m/s**:
\[ \text{Speed (u)} = 36 \, \text{km/h} = 36 \times \frac{5}{18} \, \text{m/s} = 10 \, \text{m/s} \]

3. **Determine Initial and Final Velocities**:
- Initial velocity (u) = +10 m/s (moving in the positive direction)
- Final velocity (v) = -10 m/s (reflected back in the opposite direction)

4. **Calculate Change in Momentum**:
- Initial momentum (P_i) = m × u = 0.5 kg × 10 m/s = 5 kg·m/s
- Final momentum (P_f) = m × v = 0.5 kg × (-10 m/s) = -5 kg·m/s
- Change in momentum (ΔP) = P_f - P_i = -5 kg·m/s - 5 kg·m/s = -10 kg·m/s

5. **Calculate Impulse**:
- Impulse (I) is equal to the change in momentum:
\[ I = \Delta P = -10 \, \text{kg·m/s} \]

### Final Answer:
The impulse applied on the cricket ball is **-10 kg·m/s**.

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