A boy completes one round of a circular track of radius 20 m in 50 seconds. The displacement at the end of 4 minute 10 second will be

Options

A. 40 m
B. 20 m
C. `80 pi m`
D. Zero

Answer

To solve the problem step by step, we will calculate the displacement of the boy after he completes a certain number of rounds on a circular track.

### Step 1: Understand the problem
The boy completes one round of a circular track with a radius of 20 meters in 50 seconds. We need to find the displacement after 4 minutes and 10 seconds.

### Step 2: Convert time into seconds
First, we convert the total time of 4 minutes and 10 seconds into seconds.
- 4 minutes = 4 × 60 seconds = 240 seconds
- 10 seconds = 10 seconds
- Total time = 240 seconds + 10 seconds = 250 seconds

### Step 3: Determine the number of rounds completed
Next, we need to find out how many complete rounds the boy can complete in 250 seconds.
- Time for one round = 50 seconds
- Number of rounds completed = Total time / Time for one round
- Number of rounds = 250 seconds / 50 seconds = 5 rounds

### Step 4: Analyze the displacement
Displacement is defined as the shortest distance from the initial position to the final position. Since the boy completes 5 full rounds, he ends up at the same point where he started.

### Step 5: Conclusion
Since the boy returns to his starting point after completing 5 rounds, the displacement is:
- Displacement = 0 meters

Thus, the final answer is:
**Displacement = 0 meters**

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