Question Details

In a satellite if the time of revolution is T, then kinetic energy is proportional to

Options

A

1/T

B

1/T²

C

1/T³

D

T.⁻⁶⁶⁷

Correct Answer :

T.⁻⁶⁶⁷

Solution :

The correct answer is T.⁻⁶⁶⁷.

To find how the kinetic energy of a satellite relates to its time period of revolution, we can analyze the orbital mechanics of a satellite of mass m revolving in a circular orbit of radius r around a planet of mass M.

The gravitational force between the planet and the satellite provides the centripetal force required for circular motion:

G M m r 2 = m v 2 r

where v is the orbital velocity of the satellite, and G is the universal gravitational constant. Simplifying this equation gives the orbital velocity squared:

v 2 = G M r

The kinetic energy (K) of the satellite is given by the formula:

K = 1 2 m v 2

Substituting the expression for v2 into the kinetic energy formula, we get:

K = G M m 2 r

Since G, M, and m are constants, the kinetic energy is inversely proportional to the orbital radius:

K 1 r

Next, we relate the orbital radius r to the time period of revolution T. The time period T is the time taken to complete one full orbit of circumference 2πr:

T = 2 π r v

Squaring both sides of the equation:

T 2 = 4 π 2 r 2 v 2

Substitute v2 = GM/r into the squared time period equation:

T 2 = 4 π 2 r 2 G M / r = 4 π 2 r 3 G M

This shows that T2 is proportional to r3 (Kepler's Third Law):

T 2 r 3

Solving for r, we find:

r T 2 / 3

Now, we substitute this relationship back into the proportionality for kinetic energy:

K 1 T 2 / 3 = T - 2 / 3

Since 2/3 is approximately 0.667, we can write:

K T - 0.667

This corresponds to T.⁻⁶⁶⁷.

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