Physics - Gravitation - Quiz-10

Two planets have the same density but different radii. The acceleration due to gravity would be:

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same on both planets.
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greater on the smaller planet.
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greater on the larger planet.
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dependent on the distance of the planet from the sun.

If the radius of the earth shrinks by 1.5% (mass remaining the same), then the value of the gravitational acceleration changes by:

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2%
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-2%
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3%
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-3%

If the density of a planet is double that of the earth and the radius is 1.5 times that of the earth, the acceleration due to gravity on the surface of the planet is:

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$\frac{3}{4}$ times that on the surface of the earth.
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3 times that on the surface of the earth.
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$\frac{4}{3}$ times that on the surface of the earth.
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6 times that on the surface of the earth.

The gravitational force on a body of mass 1.5 kg situated at a point is 45 N. The gravitational field intensity at that point is:

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30 N/kg
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67.5 N/kg
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46.5 N/kg
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43.5 N/kg

At what height above the surface of the earth, the value of "g" decreases by 2%?

[radius of the earth is 6400 km]

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32 km
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64 km
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128 km
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1600 km

During the motion of a man from the equator to the pole of the earth, its weight will (neglect the effect of change in the radius of the earth)

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increase by 0.34%.
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decrease by 0.34%.
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increase by 0.52%.
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decrease by 0.52%.

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

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$\frac{4 πG}{3 gR}$
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$\frac{3 πR}{4 gG}$
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$\frac{3 g}{4 πRG}$
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$\frac{πRg}{12 G}$

The value of g at the surface of the earth is 9.8 m/s². Then the value of 'g' at a place 480 km above the surface of the earth will be nearly (radius of the earth is 6400 km):

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9.8 m/s²
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7.2 m/s²
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8.5 m/s²
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4.2 m/s²

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: (x and h being much smaller than the radius of the earth)

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$x = h$
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$x = 2 h$
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$x = \frac{h}{2}$
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$x = h^{2}$

As we go from the equator to the poles, the value of 'g':

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Remains the same
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Decreases
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Increases
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First increase and then decrease

What should be the angular speed with which the earth has to rotate on its axis so that a person on the equator would weigh $\frac{3}{5}$ th as much as he weighs at present?

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$\sqrt{\frac{2 g}{5 R}}$
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$\sqrt{\frac{2 R}{5 g}}$
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$\frac{2 \sqrt{R}}{\sqrt{5 g}}$
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$\frac{2 g}{5 R}$

The acceleration due to gravity on a planet is 1.96 m/s². If it is safe to jump from a height of 3 m on the earth, the corresponding height on the planet will be:

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3 m
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6 m
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9 m
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15 m

An object is taken to height 2R above the surface of the earth, the increase in potential energy is: [R is the radius of the earth]

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$\frac{mgR}{2}$
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$\frac{mgR}{3}$
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$\frac{2 mgR}{3}$
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$2 mgR$

The change in potential energy when a body of mass m is raised to height nR from the earth's surface is: (R is the radius of the earth)

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$mgR (\frac{n}{n - 1})$
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$nmgR$
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$mgR (\frac{n}{n + 1})$
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$mgR (\frac{n^{2}}{n^{2} + 1})$

If an object is projected vertically upward with a speed equal to half the escape velocity on earth, then the maximum height attained by it is: [R is radius of earth]

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

If a satellite of mass 400 kg revolves around the earth in an orbit with a speed of 200 m/s, then its potential energy is:

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-1.2 MJ
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-8.0 MJ
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-16 MJ
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-2.4 MJ

The escape velocity of a body from the earth is about 11.2 km/s. Assuming the mass and radius of the earth to be about 81 and 4 times the mass and radius of the moon respectively, the escape velocity in km/s from the surface of the moon will be:

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0.54
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2.48
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11
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49.5

If M is the mass of a planet and R is its radius, then in order to become black hole:

[c is speed of light]

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$\sqrt{\frac{GM}{R}} \leq c$
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$\sqrt{\frac{GM}{2 R}} \geq c$
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$\sqrt{\frac{2 GM}{R}} \geq c$
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$\sqrt{\frac{2 GM}{R}} \leq c$

The atmosphere on a planet is possible only if: [where v_rms is root mean square speed of gas molecules on planet and v_e is escape speed on its surface]

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$v_{rms} = v_{e}$
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$v_{rms} > v_{e}$
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$v_{rms} \leq v_{e}$
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$v_{rms} < v_{e}$

When the speed of a satellite is increased by x percentage, it will escape from its orbit where the value of x is:

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11.2%
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41.4%
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27.5%
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34.4%

In an orbit if the time of revolution of a satellite is T, then P.E. is proportional to:

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$T^{1 / 3}$
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$T^{3}$
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$T^{- 2 / 3}$
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$T^{- 4 / 3}$

A small satellite is revolving near earth's surface. Its orbital velocity will be nearly:

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8 km/s
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11.2 km/s
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4 km/s
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6 km/s

If the potential energy of a satellite is -2 MJ, then the binding energy of the satellite is:

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1 MJ
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2 MJ
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8 MJ
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4 MJ

The time period of a polar satellite is about:

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24 hr
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100 min
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84.6 min
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6 hr

The mean radius of the earth is R and its angular speed on its axis is $ω$ . What will be the radius of orbit of a geostationary satellite?

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${(\frac{Rg}{ω^{2}})}^{1 / 3}$
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${(\frac{R^{2} g}{ω^{2}})}^{1 / 3}$
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${(\frac{R^{2} g}{ω})}^{1 / 3}$
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${(\frac{R^{2} ω^{2}}{g})}^{1 / 3}$

A satellite of the earth is revolving in a circular orbit with a uniform speed v. If the gravitational force suddenly disappears, the satellite will:

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continue to move with velocity v along the original orbit.
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move with a velocity v tangentially to the orbit.
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fall down with increasing velocity.
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ultimately come to rest somewhere on the original orbit.

The relay satellite transmits the television signals continuously from one part of the world to another because its:

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period is greater than the period of rotation of the earth.
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period is less than the period of rotation of the earth.
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period has no relation with the period of the earth about its axis.
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period is equal to the period of rotation of the earth about its axis.

If the height of a satellite from the surface of the earth is increased, then its:

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potential energy will increase.
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kinetic energy will decrease.
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total energy will increase.
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All of these

Which of the following diagrams most closely shows the variation in kinetic energy of the Earth as it moves once around the Sun in its elliptical orbit ?

Starting from the centre of the Earth having radius R, the variation of g (acceleration due to gravity) is shown by:

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Practice Physics Quiz Questions and Answers

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Practice Physics Quiz Questions and Answers

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