EASY
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Distance between two objects is quadrupled. If gravitational force between them earlier was 120 N, find the gravitational force between them now.

Important Questions on Gravitation

EASY
If the distance between two masses is doubled then the gravitational force between them will be
MEDIUM

Two masses of m each are suspended side by side at distance a, by two equal threads of length b If ’ is the angle that threads make with vertical due to attraction between masses, then α is :

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EASY
Unit of universal gravitational constant is
HARD
A straight rod of length L extends from x=a to x=L+a. The gravitational force it exerts on a point mass 'm' at x=0, if the mass per unit length of the rod is A+Bx2, is given by:
EASY

If an angel visits an asteroid called B 612 which has a radius of 20 m and mass of 104 kg, what will be the acceleration due to gravity in B 612 ?

EASY
At what height from the surface of earth the gravitation potential and the value of g are -5.4×10J kg-2 and 6.0 s-2 respectively? Take the radius of earth as 6400 km:
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The force between a hollow sphere of mass M and a point mass mat P inside it (Shown in figure): (PC=X, Radius =r

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HARD
Two satellites S1 and S2 are revolving around a planet in the opposite sense in coplanar circular concentric orbits. At time t=0, the satellites are farthest apart. The periods of revolution of S1 and S2 are 3 h and 24 h respectively. The radius of the orbit of S1 is 3×104 km. Then the orbital speed of S2 as observed from
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What is the relation between 'g' and 'G'?

HARD

In the following, the phenomena which were successfully explained by the law of gravitation are :

a) Motion of moon around the earth

b) Formation of tides

c) Motion of an aeroplane

d) Force that binds us to the earth

e) Rotation of blades in a ceiling fan

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If the change in the value of g at a height h above the surface of the earth is the same as at a depth x below it, then (both x and h being much smaller than the radius of the earth)
EASY
What is the reason for earth NOT moving towards the moon, even though moon attracts the earth?
HARD

A very long (length L) cylindrical galaxy is made of uniformly distributed mass and has radius R (R<<L). A star outside the galaxy is orbiting the galaxy in a plane perpendicular to the galaxy and passing through its centre. If the time period of the star is T and its distance from the galaxy's axis is r, then

EASY
Knowing that mass of the moon is M81, find the distance of the point from the moon, where gravitational field due to earth and the moon cancel each other. Given that distance between earth and moon =60 R , Radius of earth=R, Mass of Earth=M.
MEDIUM
Four particles, each of mass M and equidistant from each other, move along a circle of radius R under the action of their mutual gravitational attraction. The speed of each particle is
MEDIUM
Kepler's third law states that the square of the period of revolution T of a planet around the sun is proportional to the third power of the average distance r between sun and planet i.e., T2=Kr3, here K is constant. If the masses of sun and planet are M and m respectively then as per Newton's law of gravitation force of attraction between them is F=GMmr2, here G is gravitational constant. The relation between G and K is described as:
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A star mass M (equal to the solar mass) with a planet (much smaller than the star) revolves around the star in a circular orbit. The velocity of the star with respect to the centre of mass of star-planet system is shown below:

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The radius of the planet's orbit is closest to (1 AU=Distance Earth and Sun)

EASY
On halved the distance between two masses, the gravitational force between them will be:
MEDIUM
A star of mass M and radius R is made up of gases. The average gravitational pressure compressing the star due to gravitational pull of the gases making up the star depends on R as
EASY
Two spheres of mass m and M are situated in air and the gravitational force between them is f. The space around the masses is now filled with a liquid of specific gravity 4. The gravitational force will now be