Why does an astronaut experience weightlessness in outer space?

Options

A. No gravitational force acts on him
B. No frictional force acts on him
C. There is no air resistance in outer space
D. There is a vacuum in outer space

Explanation

### Step-by-Step Solution:

1. **Understanding Weight**:
- Weight is defined as the force exerted on an object due to gravity and is calculated using the formula:
\[ \text{Weight} (W) = m \cdot g \]
where \( m \) is the mass of the object and \( g \) is the acceleration due to gravity.

2. **Mass vs. Weight**:
- It's important to note that mass is an intrinsic property of an object and does not change regardless of location. Therefore, an astronaut's mass remains constant even in outer space.

3. **Gravity in Outer Space**:
- In outer space, especially when far from any massive celestial bodies, the gravitational force can be negligible. If there are no significant masses nearby, the astronaut does not experience a gravitational pull.

4. **Acceleration Due to Gravity**:
- Weightlessness occurs when there is no net force acting on the astronaut. This means that if there is no gravitational force acting on them, there is no acceleration due to gravity, leading to the sensation of weightlessness.

5. **Presence of Other Forces**:
- In outer space, there are no contact forces like friction (which requires surfaces in contact) or air resistance (which requires an atmosphere). Thus, these forces do not contribute to the astronaut's experience of weightlessness.

6. **Conclusion**:
- Since the astronaut is not experiencing any gravitational force, they feel weightless. This is because the net force acting on them is zero, and they are in a state of free fall, which is often described as weightlessness.

### Final Answer:
An astronaut experiences weightlessness in outer space because there is negligible gravitational force acting on them, leading to no net force and no acceleration due to gravity.

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