Physics - Gravitation - Quiz-3

The acceleration of a body due to the attraction of the earth (radius R) at a distance 2R

from the surface of the earth is (g = acceleration due to gravity at the surface of the

earth)

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$\frac{g}{9}$
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$\frac{g}{3}$
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$\frac{g}{4}$
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g

If V, R, and g denote respectively the escape velocity from the surface of the earth, the

radius of the earth, and acceleration due to gravity, then the correct equation is:

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$V = \sqrt{g R}$
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V= $\sqrt{\frac{4}{3} g R^{3}}$
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V = R $\sqrt{g}$
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V= $\sqrt{2 g R}$

The depth at which the effective value of acceleration due to gravity is $\frac{g}{4}$ , is:

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R
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$\frac{3 R}{4}$
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$\frac{R}{2}$
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$\frac{R}{4}$

The value of ‘g’ at a particular point is $9.8 m / s^{2}$ . Suppose the earth suddenly shrinks uniformly to half its present size without losing any mass then value of ‘g’ at the same point will now become:
(assuming that the distance of the point from the centre of the earth does not shrink)

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$4.9 m / s e c^{2}$
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$3.1 m / s e c^{2}$
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$9.8 m / s e c^{2}$
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$19.6 m / s e c^{2}$

If both the mass and the radius of the earth is decreased by 1%, then the value of the acceleration due to gravity will:

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decrease by 1%.
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increase by 1%.
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increase by 2%.
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remain unchanged.

The earth (mass = $6 \times 10^{24} k g$ ) revolves round the sun with angular velocity

$2 \times 10^{‐ 7} r a d / s$ in a circular orbit of radius $1.5 \times 10^{8} k m$ . The force exerted by the sun on

the earth in Newtons, is

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$18 \times 10^{25}$
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Zero
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$27 \times 10^{39}$
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$36 \times 10^{21}$

The value of g on the earth's surface is 980 cm/ $s e c^{2}$ . Its value at a height of 64 km from

the earth's surface is

(Radius of the earth R = 6400 kilometers)

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$960.40 c m / s e c^{2}$
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$984.90 c m / s e c^{2}$
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$982.45 c m / s e c^{2}$
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980.45 cm/ $s e c^{2}$

If the earth suddenly shrinks (without changing mass) to half of its present radius, the acceleration due to gravity will be:

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g/2
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4g
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g/4
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2g

The gravitational force between two point masses $m_{1}$ and $m_{2}$ at separation r is given by $F = k \frac{m_{1} m_{2}}{r^{2}}$ The constant k

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Depends on system of units only
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Depends on medium between masses only
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Depends on both 1 and 2
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Is independent of both 1 and 2

The density of a newly discovered planet is twice that of earth. The acceleration due to

gravity at the surface of the planet is equal to that at the surface of the earth. If the

radius of the earth is R, the radius of the planet would be

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2R
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4R
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$\frac{1}{4} R$
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$\frac{1}{2} R$

If R is the radius of the earth and g the acceleration due to gravity on the earth's surface,

the mean density of the earth is:

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$4 π G / 3 g R$
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$3 π R / 4 g G$
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$3 g / 4 π R G$
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$π R G / 12 G$

A planet has twice the radius but the mean density is $\frac{1}{4} t h$ as compared to earth. What is the ratio of escape velocity from earth to that from the planet ?

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3:1
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1:2
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1:1
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2:1

A body weighs 500 N on the surface of the earth. How much would it weigh halfway

below the surface of the earth?

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125 N
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250 N
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500 N
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1000 N

Who among the following gave first the experimental value of G?

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Cavendish
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Copernicus
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Brook Taylor
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None of these

3 particles each of mass m are kept at vertices of an equilateral triangle of side L. The

gravitational field at centre due to these particles is

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zero
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$\frac{3 G M}{L^{2}}$
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$\frac{9 G M}{L^{2}}$
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$\frac{12}{\sqrt{3}} \frac{G M}{L^{2}}$

The weight of an object in the coal mine, sea level, at the top of the mountain are $W_{1}$ ,

$W_{2}$ and $W_{3}$ respectively, then

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$W_{1} \leq W_{2} \geq W_{3}$
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$W_{1} = W_{2} = W_{3}$
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$W_{1} \leq W_{2} \leq W_{3}$
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$W_{1} \geq W_{2} \geq W_{3}$

The value of escape velocity on a certain planet is 2 km/s. Then the value of orbital speed

for a satellite orbiting close to its surface is:

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12km/s
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1km/s
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$\sqrt{2} k m / s$
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$2 \sqrt{2} k m / s$

Four particles each of mass M, are located at the vertices of a square with side L. The

gravitational potential due to this at the centre of the square is

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$- \sqrt{32} \frac{G M}{L}$
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$- \sqrt{64} \frac{G M}{L^{2}}$
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zero
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$\sqrt{32} \frac{G M}{L}$

The mass of the moon is $7.34 \times 10^{22} k g$ and the radius is $1.74 \times 10^{6} m$ . The value of

gravitation field will be

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$1.45 N / k g$
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$1.55 N / k g$
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$1.75 N / k g$
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$1.62 N / k g$

The centripetal force acting on a satellite orbiting round the earth and the gravitational

force of earth acting on the satellite both equal F. The net force on the satellite is

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Zero
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F
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$F \sqrt{2}$
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2 F

Reason of weightlessness in a satellite is:

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Zero gravity
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Centre of mass
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Zero reaction force by satellite surface
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None

Mass M is divided into two parts xM and $(1 - x) M$ . For a given separation, the value of x

for which the gravitational attraction between the two pieces becomes maximum is

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$\frac{1}{2}$
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$\frac{3}{5}$
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1
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2

If earth is supposed to be a sphere of radius R, if $g_{30 °}$ is value of acceleration due to gravity at latitude of 30^o and g at the pole, the value of $g - g_{30^{ο}}$ is

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$\frac{1}{4} ω^{2} R$
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$\frac{3}{4} ω^{2} R$
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$ω^{2} R$
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$\frac{1}{2} ω^{2} R$

If M the mass of the earth and R its radius, the ratio of the gravitational acceleration and

the gravitational constant is

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$\frac{R^{2}}{M}$
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$\frac{M}{R^{2}}$
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$M R^{2}$
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$\frac{M}{R}$

Two sphere 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 3. The

gravitational force will now be

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F
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$\frac{F}{3}$
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$\frac{F}{9}$
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3 F

Earth binds the atmosphere because of:

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Gravity
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Oxygen between earth and atmosphere
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Both 1 and 2
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4 None of these

The mass of the earth is 81 times that of the moon and the radius of the earth is 3.5

times that of the moon. The ratio of the acceleration due to gravity at the surface of the

moon to that at the surface of the earth is

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0.15
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0.0
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1
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6

Spot the wrong statement :

The acceleration due to gravity ‘g’ decreases if

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We go down from the surface of the earth towards its centre
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We go up from the surface of the earth
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We go from the equator towards the poles on the surface of the earth
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The rotational velocity of the earth is increased

Two identical solid copper spheres of radius R were placed in contact with each other. The gravitational attraction between them is proportional to:

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$R^{2}$
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$R$
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$R^{4}$
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$R^{5}$

Which of the following statements is true?

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g is less at the earth's surface than at a height above it or a depth below it
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g is the same at all places on the surface of the earth
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g has its maximum value at the equator
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g is greater at the poles than at the equator

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Practice Physics Quiz Questions and Answers

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Practice Physics Quiz Questions and Answers

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