A body suspended from a spring balance is placed in a satellite. Reading in balance is W₁ when the satellite moves in an orbit of radius R. Reading in balance is W₂ when the satellite moves in an orbit of radius 2R . Then
Correct Answer :
W₁ = W₂
Solution :
The correct option is W₁ = W₂.
Let's understand the physical principles behind this result step-by-step:
1. Concept of Weightlessness in a Satellite:
When a satellite orbits the Earth, it is in a state of continuous free fall towards the Earth. The gravitational force acting on any object of mass inside the satellite provides the centripetal acceleration required to keep it in its circular orbit.
The gravitational acceleration at an orbital radius is given by:
where is the universal gravitational constant and is the mass of the Earth.
2. Analyzing the forces on the suspended body:
For a body of mass suspended from a spring balance inside the satellite, the forces acting on it are:
- The gravitational force pulling it towards the center of the Earth:
- The tension or restoring force exerted by the spring balance, which represents the weight reading of the balance.
Since the body moves in the orbit with the same acceleration as the satellite, we write the equation of motion as:
Substituting the values of gravitational force and acceleration :
Simplifying the equation, we get:
3. Comparing the readings at different radii:
Since the reading of the spring balance is zero, it remains zero regardless of the radius of the orbit.
- At orbital radius , the reading is .
- At orbital radius , the reading is .
Therefore:
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