Physics - Gravitation - Quiz-2

The escape velocity from the surface of the earth is $v_{e}$ . The escape velocity from the surface of a planet whose mass and radius are 3 times those of the earth will be:

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$v_{e}$
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3 $v_{e}$
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9 $v_{e}$
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27 $v_{e}$

How much energy will be necessary for making a body of 500 kg escape from the earth?

[g = 9.8 m / s^{2}, r a d i u s o f e a r t h = 6.4 \times 10^{6} m]

(a) $A b o u t 9.8 \times 10^{6} J$ (b) $A b o u t 6.4 \times 10^{8} J$

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1
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2
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3
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4

Two planets have the same average density but their radii are $R_{1}$ and $R_{2}$ . If acceleration due to gravity on these planets be $g_{1}$ and $g_{2}$ respectively, then

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$\frac{g_{1}}{g_{2}}$ = $\frac{R_{1}}{R_{2}}$
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$\frac{g_{1}}{g_{2}}$ = $\frac{R_{2}}{R_{1}}$
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$\frac{g_{1}}{g_{2}}$ = $\frac{{R_{1}}^{2}}{{R_{2}}^{2}}$
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$\frac{g_{1}}{g_{2}}$ = $\frac{{R_{1}}^{3}}{{R_{2}}^{3}}$

Assume that the acceleration due to gravity on the surface of the moon is 0.2 times the acceleration due to gravity on the surface of the earth. If $R_{E}$ is the maximum range of a projectile on the earth’s surface, what is the maximum range on the surface of the moon for the same velocity of projection ?

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() 0.2 $R_{ε}$
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() 2 $R_{ε}$
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() 0.5 $R_{ε}$
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() 5 $R_{ε}$

If the density of the earth is increased 4 times and its radius becomes half of what it is, our weight will be:

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four times the present value.
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doubled.
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the same.
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Halved.

The escape velocity on earth is 11.2 km/s. On another planet having twice radius and 8 times mass of the earth, the escape velocity will be

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() 3.7 km/s
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() 11.2 km/s
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() 22.4 km/s
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() 43.2 km/s

When a body is taken from the equator to the poles, its weight

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Remains constant
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Increases
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Decreases
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Increases at N-pole and decreases at S-pole

The escape velocity of a body on the surface of the earth is 11.2 km/s. If the earth's mass increases to twice its present value and the radius of the earth becomes half, the escape velocity would become

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5.6 km/s
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11.2 km/s (remain unchanged)
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22.4 km/s
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44.8 km/s

A body of mass m is taken to the bottom of a deep mine. Then

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Its mass increases
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Its mass decreases
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Its weight increases
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Its weight decreases

Given mass of the moon is 1/81 of the mass of the earth and corresponding radius is 1/4 of the earth. If escape velocity on the earth surface is 11.2 km/s, the value of same on the surface of the moon is

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0.14 km/s
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0.5 km/s
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2.5 km/s
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5 km/s

The angular velocity of rotation of star (of mass M and radius R) at which the matter start to escape from its equator will be

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$\sqrt{\frac{2 G M^{2}}{R}}$
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$\sqrt{\frac{2 G M}{g}}$
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$\sqrt{\frac{2 G M}{R^{3}}}$
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$\sqrt{\frac{2 G R}{M}}$

A body weighs 700 gm wt on the surface of the earth. How much will it weigh on the surface of a planet whose mass $\frac{1}{7}$ of earth's mass and radius is half that of the earth ?

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200 gm wt
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400 gm wt
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50 gm wt
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300 gm wt

What will be the acceleration due to gravity at height h if h >> R where R is radius of earth and g is acceleration due to gravity on the surface of earth ?

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$\frac{g}{{(1 + \frac{h}{R})}^{2}}$
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$g (1 - \frac{2 h}{R})$
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$\frac{g}{{(1 - \frac{h}{R})}^{2}}$
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$g (1 - \frac{h}{R})$

How many times is escape velocity, of orbital velocity for a satellite revolving near earth?

(a) $\sqrt{2}$ times (b) 2 times

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1
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2
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3
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4

The acceleration due to gravity near the surface of a planet of radius R and density d is

proportional to

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$\frac{d}{R^{2}}$
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$d R^{2}$
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dR
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$\frac{d}{r}$

The weight of a body at the centre of the earth is -

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Zero
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Infinite
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Same as on the surface of the earth
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None of the above

If the radius of a planet is R and its density is $ρ$ , the escape velocity from its surface will

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$V_{e} \propto p R$
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$V_{e} \propto R \sqrt{ρ}$
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$V_{e} \propto \frac{\sqrt{p}}{R}$
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$V_{e} \propto \frac{1}{\sqrt{p} R}$

If the distance between two masses is doubled, the gravitational attraction between them:

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Is doubled
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Becomes four times
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Is reduced to half
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Is reduced to a quarter

If the earth stops rotating, the value of ‘g’ at the equator will

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Increase
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Remain same
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Decrease
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None of the above

If acceleration due to gravity on the surface of a planet is two times that on surface of

earth and its radius is double that of earth. Then escape velocity from the surface of that

planet in comparison to earth will be -

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2v_e
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3v_e
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4v_e
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None of these

A body weight W newton at the surface of the earth. Its weight at a height equal to half

the radius of the earth will be

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$\frac{w}{2}$
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$2 \frac{w}{3}$
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$4 \frac{w}{9}$
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$\frac{8 w}{27}$

The escape velocity of a rocket launched from the surface of the earth

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Does not depend on the mass of the rocket
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Does not depend on the mass of the earth
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Depends on the mass of the planet towards which it is moving
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None of the above

Which of the following is the evidence to show that there must be a force acting on earth

and directed towards the sun?

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Deviation of the falling bodies towards east
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Revolution of the earth around the sun
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Phenomenon of day and night
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The apparent motion of the sun around the earth

A mass of $6 \times 10^{24} k g$ is to be compressed in a sphere in such a way that the escape

velocity from the sphere is $3 \times 10^{8} m / s$ . Radius of the sphere should be

$(G = 6.67 \times 10^{- 11} N - m^{2} / k g^{2})$

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9 km
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9 m
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9 cm
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9 mm

The mass and diameter of a planet have twice the value of the corresponding parameters

of earth. Acceleration due to gravity on the surface of the planet is

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$9.8 m / s e c^{2}$
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$4.9 m / s e c^{2}$
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$980 m / s e c^{2}$
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$19.6 m / s e c^{2}$

Force of gravity is least at

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The equator
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The poles
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A point in between the equator and any pole
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None of these

The velocity with which a projectile must be fired so that it escapes earth’s gravitation

does not depend on:

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Mass of the earth
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Mass of the projectile
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Radius of the projectile’s orbit
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Gravitational constant

The gravitational force between two stones of mass 1 kg each separated by a distance of

1 metre in vacuum is

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Zero
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6.675 $\times 10^{‐ 5} n e w t o n$
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$6.675 \times 10^{‐ 11} n e w t o n$
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$6.675 \times 10^{‐ 8} n e w t o n$

The escape velocity for the Earth is taken $v_d$. Then, the escape velocity for a planet whose radius is four times and the density is nine times that of the earth, is:

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$36 v_{d}$
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$12 v_{d}$
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$6 v_{d}$
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$20 v_{d}$

Two particles of equal mass go round a circle of radius R under the action of their mutual

gravitational attraction. The speed of each particle is

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$ν = \frac{1}{2 R} \sqrt{\frac{1}{G m}}$
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$ν = \sqrt{\frac{G m}{2 R}}$
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$ν = \frac{1}{2} \sqrt{\frac{G m}{R}}$
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$ν = \sqrt{\frac{4 G m}{R}}$

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Practice Physics Quiz Questions and Answers

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Practice Physics Quiz Questions and Answers

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