Question Details

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

Options

A

W₁ = W₂

B

W₁ > W₂

C

W₁ < W₂

D

W₁ = 2W₂

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 m inside the satellite provides the centripetal acceleration required to keep it in its circular orbit.

The gravitational acceleration at an orbital radius r is given by:
a = G M r 2
where G is the universal gravitational constant and M is the mass of the Earth.

2. Analyzing the forces on the suspended body:
For a body of mass m 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:
F g = G M m r 2
- The tension or restoring force exerted by the spring balance, which represents the weight reading W of the balance.

Since the body moves in the orbit with the same acceleration a as the satellite, we write the equation of motion as:
F g - W = m a

Substituting the values of gravitational force Fg and acceleration a:
G M m r 2 - W = m G M r 2

Simplifying the equation, we get:
W = 0

3. Comparing the readings at different radii:
Since the reading W of the spring balance is zero, it remains zero regardless of the radius of the orbit.
- At orbital radius R, the reading is W1=0.
- At orbital radius 2R, the reading is W2=0.

Therefore:
W 1 = W 2

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