Why do bodies become weightless in artificial satellites ?

Answer

### Step-by-Step Solution:

1. **Understanding the Concept of Weightlessness**:
- Weightlessness occurs when an object is in free fall, meaning it is only influenced by gravity and is not experiencing any normal force acting upon it.

2. **Artificial Satellite in Orbit**:
- An artificial satellite orbits the Earth due to the gravitational force acting on it. The satellite moves in a circular path, and its speed is such that the gravitational pull provides the necessary centripetal force to keep it in orbit.

3. **Free Body Diagram**:
- In the case of the satellite, we can draw a free body diagram. The only force acting on the satellite (and any object inside it) is the gravitational force (weight) directed downwards.

4. **Frame of Reference**:
- When we analyze the situation from the frame of the satellite, we consider the effects of gravity and the pseudo forces that arise due to the acceleration of the satellite.

5. **Calculating Forces**:
- Let’s denote the mass of an object inside the satellite as \( M \). The gravitational force acting on it is \( F_g = M \cdot g \), where \( g \) is the acceleration due to gravity.
- In the satellite's frame, the gravitational force is balanced by the acceleration of the satellite. Since the satellite is in free fall, the normal force \( N \) acting on the object is zero.

6. **Conclusion**:
- Since the normal force \( N = 0 \), the object does not experience any contact force pushing against it. Therefore, it feels weightless. This is similar to being in a free-falling elevator where the normal force also becomes zero.