Statement-1 : Karman Malleshwari famous indian weight lifter lifts a weight up and returns it to same initial position along the same path. Net work done by muscles of weight lifter is positive.
Statement-2 : Net displacement of weight is zero.

Options

A. Statement-1 is true.
B. Statement-1 is false.
C. Statement-2 is true.
D. Statement-2 is false.

Answer

To analyze the statements provided, we will break down the concepts of work done, displacement, and the implications of lifting and returning a weight.

**Step 1: Understanding Work Done**
Work done (W) is defined as the product of the force applied (F) and the displacement (d) in the direction of the force. Mathematically, it can be expressed as:
\[ W = F \cdot d \cdot \cos(\theta) \]
where \( \theta \) is the angle between the force and the direction of displacement.

**Step 2: Analyzing Statement 1**
In the case of Karman Malleshwari lifting a weight:
- When she lifts the weight, she applies an upward force that is equal to the weight of the object (mg, where m is mass and g is acceleration due to gravity).
- The displacement is also upward.
- Therefore, the work done while lifting the weight is positive because the force and displacement are in the same direction.

**Step 3: Analyzing the Return Journey**
When she returns the weight to the initial position:
- The weight is moved downward, and the force exerted by the muscles is still upward.
- The displacement is downward while the force is upward, making the angle \( \theta = 180^\circ \).
- The work done during this phase is negative because the force and displacement are in opposite directions.

**Step 4: Net Work Done**
The net work done by the muscles over the entire process (lifting and returning) can be calculated as:
\[ W_{net} = W_{up} + W_{down} \]
Since \( W_{up} \) is positive and \( W_{down} \) is negative, the net work done is zero because they cancel each other out.

**Step 5: Analyzing Statement 2**
Statement 2 states that the net displacement of the weight is zero. This is true because the weight is lifted and then returned to the same initial position, resulting in no overall change in position.

**Conclusion: Evaluating Statements**
- Statement 1 is **false** because the net work done by the muscles is zero, not positive.
- Statement 2 is **true** because the net displacement is indeed zero.

Thus, the correct conclusion is that Statement 1 is incorrect, and Statement 2 is correct.