Q. A planet is revolving round the sun in an elliptical orbit. Of the following, the property which is a constant during the motion of the planet is :

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A

The force of attraction between the planet and sun.

B

The total energy of the "planet plus sun" system.

C

The linear momentum of the planet.

D

The kinetic energy of the planet about the sun.

Solution:

Total energy and angular momentum of a planet+sun system remain conserved hence option (B) is correct.

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2. Assertion : Planet is a heavenly body revolving round the sun.
Reason : Star is luminous body made of gaseous material.

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3. If $W_1$, $W_2$ and $W_3$ represent the work done in moving a particle from $A$ to $B$ along three different paths $1$, $2$ and $3$ (as shown in fig) in the gravitational field of the point mass $'m'$. Find the correct relation between $'W'_1$, $'W_2'$ and $'W_3'$

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4. A projectile is fired from the surface of the Earth of radius $R$ with a velocity $\eta v_{e}$ , where $v_{e}$ is the escape velocity and $\eta < 1$ . Neglecting the air resistance, the orbital velocity of the projectile is

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5. The effect of rotation of the Earth on the value of acceleration due to gravity is

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