NEET UG PHYSICS MCQ: GRAVITATION

1 Hard

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Analyzing +4 | -1

An artificial satellite of mass

m

of a planet (radius

R

, mass

{M})

revolves in a circular orbit whose orbital radius in

n

times the radius of the planet. In the process of motion, the satellite experiences a slight resistance due to cosmic dust. Assuming the resistive force

{F}={kv}^2

, where

{k}

is a constant and

v

the instantaneous velocity. The time taken by the satellite to fall from its orbit to the surface of the planet is found

\frac{m}{k} \sqrt{\frac{R}{G m}}(y \sqrt{n}-1)

. Find

y

View answer and explanation

Correct option: A

Option A (1) is correct because the time taken for the satellite to fall is derived from the resistive force and orbital mechanics, leading to y=1.

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If a particle of mass m is moving in a horizontal circle of radius r with a centripetal force

\left( { - K/{r^2}} \right)

the total energy is Suppose the law of gravitational attraction suddenly changes and becomes an inverse cube law i.e.

F \propto \frac{1}{r^3}

, but still remaining a central force. Then Two satellites A and B go round a planet P is circular orbits having radii 16 R and 2 R respectively. If the speed of satellite A is

6\,m{s^{ - 1}}

the speed of the satellite B will be [in m/s] nearly The total energy of satellite moving with an orbital velocity

v

around the earth is Two satellites of same mass are launched in the same orbit of radius

r

around the earth so as to rotate opposite to each other. If they collide inelastically and stick together as wreckage, the total energy of the system just after collision is Statement-1: There is almost no effect of rotation of earth at poles.
Statement-2: Because rotation of earth is about polar axis.