A body of mass 1 kg is rotated in a horizontal circle of radius 1 m and moves with velocity `2 ms^(-1)` The work done in 10 revolutions is

Options

A. 40 J
B. 20 J
C. `4xx2pi(10) J`
D. zero

Answer

To solve the problem of calculating the work done in 10 revolutions by a body of mass 1 kg rotating in a horizontal circle of radius 1 m with a velocity of 2 m/s, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Motion**:
The body is moving in a circular path. After completing 10 revolutions, it returns to its initial position.

2. **Displacement Calculation**:
Since the body returns to its starting point after 10 revolutions, the net displacement is zero. Displacement is defined as the shortest distance from the initial to the final position.

3. **Work Done Formula**:
The work done \( W \) is given by the formula:
\[ W = F \cdot d \]
where \( F \) is the force applied and \( d \) is the displacement.

4. **Force Analysis**:
In circular motion, the only force acting on the body (tension in the string or centripetal force) is directed towards the center of the circle. This force is always perpendicular to the direction of motion (tangential direction).

5. **Work Done Calculation**:
Since the displacement after 10 revolutions is zero, the work done is:
\[ W = F \cdot 0 = 0 \]

6. **Conclusion**:
Therefore, the work done in 10 revolutions is zero.

### Final Answer:
The work done in 10 revolutions is \( 0 \, \text{J} \).

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