STATEMENT -1: Work done on a body A by B must be equal and opposite and the work done by A on B
STATEMENT-2: if body undergoes a displacement under the action of a force, then the force must have done some work.
STATEMENT-3: When we climb the stairs, it is the work done by the stairs which increases our potential energy.

Options

A. F F F
B. T T T
C. T T F
D. F T F

Answer

To analyze the given statements, let's break them down one by one and determine their validity based on the principles of work and energy in physics.

### Step 1: Analyze Statement 1
**Statement 1:** Work done on a body A by B must be equal and opposite to the work done by A on B.

- According to Newton's third law, for every action, there is an equal and opposite reaction. This means that if body A exerts a force on body B, body B exerts an equal and opposite force on body A.
- However, the work done depends on the displacement and the direction of the force. If body A is falling under gravity, the work done by gravity on A is positive (as it moves downwards), while the work done by A on the Earth is zero (as the Earth does not move).
- Therefore, Statement 1 is **false**.

### Step 2: Analyze Statement 2
**Statement 2:** If a body undergoes a displacement under the action of a force, then the force must have done some work.

- Work done is defined as the product of the force and the displacement in the direction of the force (W = F × d × cos(θ)). If the force is acting on the body but there is no displacement (for example, if the force is perpendicular to the displacement), then the work done is zero.
- Thus, it is possible for a force to act on a body without doing any work if there is no displacement in the direction of the force.
- Therefore, Statement 2 is **false**.

### Step 3: Analyze Statement 3
**Statement 3:** When we climb the stairs, it is the work done by the stairs which increases our potential energy.

- When a person climbs stairs, they are doing work against the gravitational force, which increases their potential energy. The work done by the person (not the stairs) is what increases their potential energy.
- The stairs provide a support force but do not do work on the person in the sense of increasing potential energy. The work done is by the person climbing the stairs.
- Therefore, Statement 3 is **false**.

### Conclusion
All three statements are false based on the analysis above.

### Final Answer
All the statements are false.

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