A boy is standing on a truck moving with a constant velocity of `15 m//s` on the horizontal road. The boy throws a ball in such a way that it returns to the truck after the truck has moved `60 m`. Find the speed and the angle of projection (a) as seen by the truck and (b) as seen from the road.

Explanation

To solve the problem, we need to analyze the motion of the ball from two different reference frames: the truck (which is moving) and the ground (which is stationary).

### Step-by-Step Solution

#### Step 1: Analyze the motion from the ground frame
1. **Given Data**:
- Velocity of the truck, \( v_t = 15 \, \text{m/s} \)
- Distance moved by the truck, \( d = 60 \, \text{m} \)
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