If a stone projected from ground, takes 4 s to reach the topmost point, of its trajectory, then time of fight is

Options

A. 4 s
B. 8 s
C. 2 s
D. 10 s

Answer

To solve the problem of finding the total time of flight for a stone projected from the ground, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Problem**:
- The stone takes 4 seconds to reach the topmost point of its trajectory.
- We need to find the total time of flight.

2. **Time to Reach Maximum Height**:
- The time taken to reach the maximum height (topmost point) is given as \( t_{up} = 4 \, \text{s} \).

3. **Time to Descend**:
- The time taken to descend from the maximum height back to the ground is equal to the time taken to ascend to the maximum height in projectile motion. Therefore, the time to descend \( t_{down} = t_{up} = 4 \, \text{s} \).

4. **Total Time of Flight**:
- The total time of flight \( T \) is the sum of the time taken to go up and the time taken to come down:
\[ T = t_{up} + t_{down} = 4 \, \text{s} + 4 \, \text{s} = 8 \, \text{s} \]

5. **Conclusion**:
- The total time of flight for the stone is \( T = 8 \, \text{s} \).

### Final Answer:
The total time of flight is **8 seconds**.

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