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, we need to determine the total time of flight for a stone projected upwards, given that it takes 4 seconds to reach the topmost point of its trajectory.

### Step-by-Step Solution:

1. **Understanding the Motion**:
- When a stone is projected upwards, it takes time to reach the highest point (topmost point) where its vertical velocity becomes zero. After reaching the highest point, it will take the same amount of time to come back down to the ground.

2. **Given Information**:
- Time taken to reach the topmost point = 4 seconds.

3. **Time of Flight Calculation**:
- The total time of flight (T) is the sum of the time taken to go up (T_up) and the time taken to come down (T_down).
- Since the time taken to go up is equal to the time taken to come down, we have:
\[ T = T_{up} + T_{down} = 4 \, \text{s} + 4 \, \text{s} = 8 \, \text{s} \]

4. **Final Answer**:
- Therefore, the total time of flight is:
\[ T = 8 \, \text{seconds} \]