Question Details

The eccentricity of earth’s orbit is 0.0167. The ratio of its maximum speed in its orbit to its minimum speed is

Options

A

2.507

B

1.033

C

8.324

D

1.000

Correct Answer :

1.033

Solution :

The correct option is 1.033.

Step-by-step Explanation:

According to Kepler's second law of planetary motion, the areal velocity of a planet revolving around the Sun in an elliptical orbit remains constant. This is a direct consequence of the conservation of angular momentum. Since no external torque acts on the system, the angular momentum of the planet about the Sun is conserved.

The angular momentum (L) of the Earth at any point in its orbit is given by:
L=m·v·r
where:
m is the mass of the Earth,
v is the orbital speed of the Earth, and
r is the distance of the Earth from the Sun.

At the closest point to the Sun (perihelion), the distance is minimum (rmin) and the speed is maximum (vmax). At the farthest point from the Sun (aphelion), the distance is maximum (rmax) and the speed is minimum (vmin).

By the conservation of angular momentum:
m·vmax·rmin=m·vmin·rmax
Simplifying this relation, we find the ratio of maximum speed to minimum speed:
vmaxvmin=rmaxrmin

For an elliptical orbit with semi-major axis a and eccentricity e, the minimum and maximum distances are defined as:
rmin=a(1-e)
and
rmax=a(1+e)

Substituting these expressions into the speed ratio formula:
vmaxvmin=a(1+e)a(1-e)=1+e1-e

Given that the eccentricity of the Earth's orbit is e=0.0167, we substitute this value into the equation:
vmaxvmin=1+0.01671-0.0167
vmaxvmin=1.01670.98331.03397

Rounding this ratio to three decimal places yields approximately 1.033.

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