The driver of a three wheeler moving with a speed of `36 km//h` sees a child standing in the middle of the road and brings his vehicle to rest in 4 s just in time to save the child What is the average retarding force on the vechicle ? The mass of three wheeler is 400 kg and mass of the driver is 65 kg .

Explanation

To solve the problem, we need to find the average retarding force exerted on the three-wheeler as it comes to a stop. Here’s a step-by-step breakdown of the solution:

### Step 1: Convert the speed from km/h to m/s
The initial speed of the three-wheeler is given as 36 km/h. We need to convert this to meters per second (m/s).

\[ \text{Speed in m/s} = \frac{36 \text{ km/h} \times 1000 \text{ m/km}}{3600 \text{ s/h}} = 10 \text{ m/s} \]
...