To understand why bodies become weightless in artificial satellites, we can break down the explanation into several steps:
### Step 1: Understanding Weight
Weight is the force exerted on an object due to gravity. It is calculated using the formula:
\[
W = mg
\]
where \( W \) is weight, \( m \) is mass, and \( g \) is the acceleration due to gravity.
### Step 2: Concept of Free Fall
When an object is in free fall, it is falling under the influence of gravity alone, without any other forces acting on it. In this situation, the only force acting on the object is its weight, which causes it to accelerate downwards at \( g \).
### Step 3: The Elevator Analogy
Imagine an elevator that is in free fall. Inside this elevator, if you were to drop an object, both the object and the elevator would fall at the same rate due to gravity. In this scenario, the object does not exert any force on the floor of the elevator, and therefore, it does not experience any normal force.
### Step 4: Apparent Weight
The apparent weight of an object is the weight that is measured by a scale. In the case of the free-falling elevator, the normal force (which is what scales measure) is zero because the object is not pushing against the scale. Thus, the scale would read zero, indicating that the object is weightless.
### Step 5: Application to Artificial Satellites
Artificial satellites are in a state of continuous free fall towards the Earth. However, they also have a horizontal velocity that keeps them in orbit. As they fall towards the Earth, they move forward at such a speed that they keep missing the Earth. This creates a condition similar to the free-fall scenario described earlier.
### Step 6: Conclusion
Since both the satellite and the objects inside it (including astronauts) are in free fall, they experience weightlessness. The apparent weight of these objects is zero because there is no normal force acting on them, similar to the situation in the free-falling elevator.
### Final Answer
Bodies become weightless in artificial satellites because they are in a continuous state of free fall, similar to being in an elevator that is falling freely. In this condition, the normal force is zero, resulting in an apparent weight of zero.
---
