A stone is thrown vertically from the ground. It reaches the maximum height of 500 m in 10 sec. After what time it will reach the ground from the maximum height reached?

Options

A. 5 s
B. 10s
C. 15 s
D. 20 s

Answer

To solve the problem of a stone thrown vertically upwards that reaches a maximum height of 500 m in 10 seconds, we can follow these steps:

### Step 1: Understand the motion
When the stone is thrown upwards, it takes time to reach the maximum height where its velocity becomes zero. The time taken to reach the maximum height is equal to the time taken to fall back down to the ground from that height.

### Step 2: Identify the time taken to reach maximum height
From the problem statement, we know that the stone takes 10 seconds to reach the maximum height of 500 m.

### Step 3: Determine the time taken to fall back to the ground
Since the time taken to go up is equal to the time taken to come down, the time taken to fall back to the ground from the maximum height will also be 10 seconds.

### Step 4: Calculate the total time of flight
The total time of flight for the stone from the ground to the maximum height and back to the ground is:
- Time to reach maximum height = 10 seconds
- Time to fall back to ground = 10 seconds

Thus, the total time of flight = 10 seconds (up) + 10 seconds (down) = 20 seconds.

### Final Answer
The stone will take **10 seconds** to reach the ground from the maximum height reached.

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