A hockey ball of mass `200 g` travelling at `10 m//s` is struck by a hockey stick so as to return it along its original path with a velocity of `5 m//s`. Calculate the change in momentum of the hockey ball by the force applied by the hockey stick.

Explanation

To calculate the change in momentum of the hockey ball when it is struck by the hockey stick, we will follow these steps:

### Step 1: Convert mass to SI units
The mass of the hockey ball is given as `200 g`. To convert this to kilograms (the SI unit for mass), we use the conversion factor \(1 \, \text{kg} = 1000 \, \text{g}\).

\[ \text{Mass} = \frac{200 \, \text{g}}{1000} = 0.2 \, \text{kg} \]
...