2788 + Interview Questions in GRAVITATION IN GENERAL AWARENESS Page 14 InterviewSolution

651.	Two concentric shells of masses `M_(1)` and `M_(2)` are having radii `r_(1)` and `r_(2)`. Which of the following is the correct expression for the gravitational field on a mass `m`? A. `F=(G(M_(1)+M_(2)))/(r^(2))`, for `rltr_(1)`B. `F=(G(M_(1)+M_(2)))/((r^(2))`, for `rltr_(2)`C. `F=(GM_(2))/(r^(2))`, for `r_(1)ltrltr_(2)`D. `F=GM_(1)/(r^(2))`, for `r_(1)ltrltr_(2)`
Answer» Correct Answer - C Gravitational field inside a shell is zero, but for points outside it, the shell behaves as if whole of its mass is concentrated at its centre. Hence, for a point lying in between the shells there will be a field only due to the inner shell `(=GM_(2)//r^(2))` because the point will be an external point for the inner shell but internal for the outer shell.

Discussion

652.	Write the formula to find the magnitude of the gravitational force between the Earth and an object on the surface of the Earth.
Answer» Gravitanal force ,`F=Gxx(Mxxm)/(R^(2))` where G=Gravitational constant M=Mass of the earth m=mass of the object and R=Radius of the earth

Discussion

653.	Choose the correct statement about gravitational forceA. It forms action-reaction pairB. It is a central forceC. It is a conservative forceD. It is independent of the medium between the masses
Answer» Correct Answer - A::B::C::D

Discussion

654.	The correct graph representing the variation of total energy `(E_(t))`, kinetic energy `(E_(k))` and potential energy `(U)` of a satellite with its distance form the centre of earth isA. B. C. D.
Answer» Correct Answer - C `U= -(GMm)/r, K=(GMm)/(2r)` and `E=(-GMm)/(2r)` For a satellite `U,K` and `E` very with `r` and also `U` and `E` remain negative whereas `K` remain always positive

Discussion

655.	The correct graph representing the variation of total energy `(E_(t))`, kinetic energy `(E_(k))` and potential energy `(U)` of a satellite with its distance form the centre of earth isA. B. C. D.
Answer» Correct Answer - C

Discussion

656.	Identify the correct statementsA. The Earth always act like a point massB. To an apple, the Earth acts like a point massC. To a satellite, the Earth acts acts like point massD. To moon, the Earth acts like a point mass
Answer» Correct Answer - B::C::D

Discussion

657.	A satellite is revolving in circular orbit of radius `r` around the earth of mass M. Time of revolution of satellite isA. `Tprop(r^(5))/(GM)`B. `T propsqrt((r^(3))/(GM))`C. `T prop sqrt((r)/((GM^(2))/(3)))`D. `T prop sqrt((r^(3))/((GM)/(4)))`
Answer» Correct Answer - B The time period of revolution of satellite is given by `rArr T=2pisqrt((r^(3))/(GM))rArr T=prop sqrt((r^(3))/(GM))`.

Discussion

658.	The period of a satellite moving in a circular orbit near the surface of a planet is independent ofA. mass of the planetB. radius of the planetC. mass of the satelliteD. density of planet
Answer» Correct Answer - C

Discussion

659.	The period of a satellite in a circular orbit around a planet is independent ofA. the mass of the planetB. the radius of the planetC. the mass of the satelliteD. All the three parameters (a), (b) and (c)
Answer» Correct Answer - C The time period of satellite in a circular orbit ground a planet is independent of mass of satellite,

Discussion

660.	The period of a satellite moving in a circular orbit near the surface of a planet is independent ofA. The mass of the planetB. The radius of the planetC. The mass of the satelliteD. All the three parameters (a), (b) and (c)
Answer» Correct Answer - C

Discussion

661.	The period of a satellite moving in a circular orbit near the surface of a planet is independent ofA. radius of the planetB. mass of the planetC. mass of the satelliteD. none of the above
Answer» Correct Answer - C `T=(2pi(r+h)^(3//2))/(sqrt(GM))=(2pir^(3//2))/(sqrt(GM))`

Discussion

662.	Time period of a satellite in a circular obbit around a planet is independent ofA. Radius of the orbitB. Mass of the planetC. Mass of the statelliteD. Radius of the planet
Answer» Correct Answer - C::D

Discussion

663.	Orbital radius of a satellite S of earth is four times that s communication satellite C. Period of revolution of S is :-A. 4 daysB. 8 daysC. 16 daysD. 32 days
Answer» Correct Answer - B

Discussion

664.	The period of revolution of an earth satellite close to surface of earth is 90min. The time period of aother satellite in an orbit at a distance of three times the radius of earth from its surface will beA. `90sqrt(8)min`B. `360min`C. `720min`D. `270min`
Answer» Correct Answer - C

Discussion

665.	Three identical particles force exerted on one body due to the other two.
Answer» Correct Answer - `sqrt(3) (Gm^(2))/a^(2)`

Discussion

666.	Which one of the following graphs represents correctly represent the variation of the gravitational field (E) with the distance (r) from the centre of a spherical shell of mass M radius R ?A. B. C. D.
Answer» Correct Answer - D Intensity will be zero inside the spherical shell. E= 0 upto r = R and `E prop (1)/(r^(2)) "when" r gt R`.

Discussion

667.	Three identical point mass each of mass 1kg lie in the x-y plane at point (0,0), (0,0.2m) and (0.2m, 0). The net gravitational force on the mass at the origin isA. `1.67xx10^(-11) (hat(i)+hat(j))N`B. `3.34xx10^(-10) (hat(i)+hat(j))N`C. `1.67xx10^(-9) (hat(i)+hat(j))N`D. `3.34xx10^(-10) (hat(i)-hat(j))N`
Answer» Correct Answer - C

Discussion

668.	Energy of a satellite in circular orbit is `E_(0)`. The energy required to move the satellite to a circular orbit of 3 times the radius of the initial orbit isA. `(2)/(3)E_(0)`B. `2E_(0)`C. `(E_(0))/(3)`D. `(3)/(2)E_(0)`
Answer» Correct Answer - A `E_(i)-E_(0)=-(GMm)/(2r) or E_(f)=-(GMm)/(2(3r))=-(GMm)/(6r)` `:. W=E_(f)-E_(j)=-(GMm)/(3r)=(2)/(2)E_(0)`.

Discussion

669.	Four equal masses (each of mass M) are placed at the corners of a squares side a the escape velocity of a body from the centre O of the square isA. `4sqrt(2GM)/(a)`B. `sqrt(8sqrt(2GM))/(a)`C. `(4GM)/(a)`D. `sqrt(4sqrt(2)GM)/(a)`
Answer» Correct Answer - B Potential at centre `=-(4GM)/(r )=(-4GM)/(a//sqrt(2))=-(4sqrt(2)GM)/(a)` `PE=(-4sqrt(2)GMm)/(a)` `BE=(4sqrt(2)GMm)/(a)` `therefore 1/2mv_(e)^(2)=(4sqrt(2)GMm)/(a)` `rarr v_(e )=sqrt(8sqrt(2)GM)/(a)`

Discussion

670.	The weight of a body at the centre of the earth isA. zeroB. infiniteC. same as no the surface of earthD. None of the above
Answer» Correct Answer - A At centre of earth, value of `g` is zero. Hence, weight is zero.

Discussion

671.	The diagram showing the variation of gravitational potential of earth with distance from the centre of earth isA. B. C. D.
Answer» Correct Answer - C

Discussion

672.	The correct variation of gravitational potential `V` with radius `r` measured from the centre of earth of radius `R` is given byA. B. C. D.
Answer» Correct Answer - B `V(r)=-(GM)/(r),r ge R=-(GM)/(2R^(3))(3R^(2)-r^(2)),r lt R`

Discussion

673.	The relative densities of four liquids P,Q,R and S are 1.26,1.0,0.84, and 13.6 respectively .An object is floated in all these liquids ,one by one .In which liquid will is maximum volume submerged under the liquid ?A. PB. QC. RD. S
Answer» Correct Answer - C

Discussion

674.	Two identical spheres are placed in contact with each other. The force of gravitation between the spheres will be proportional to ( R = radius of each sphere)A. RB. `R^(2)`C. `R^(4)`D. `1//R^(2)`
Answer» Correct Answer - c `F=("GMn")/(R^(2))=(G((4)/(3)piR^(3)rho)^(2))/((2R^(2)))prop (R^(6))/(R^(2))prop R^(4).`

Discussion

675.	Two bodies of masses M and m are allowed to fall from the same height . If air resistance for each body be same , will the two bodies reach the ground simultaneously ?A. the ratio of the massesB. the inverse of the ratio of their massesC. oneD. product of their masses
Answer» Correct Answer - c Acceleration due to gravity is independent of mass of the bodies.

Discussion

676.	What is the weight of a 1 kilogram mass on the earth? `(g = 9 .8 m//s^2).
Answer» Correct Answer - 9.8 N

Discussion

677.	What is the weight of a 1 kilogram mass on the earth ? (g = 9.8 m/s2 ).
Answer» Weight, W = m x g = 1 kg x 9.8m/s² =9.8 N

677.

What is the weight of a 1 kilogram mass on the earth ? (g = 9.8 m/s2 ).

Answer»

Weight, W = m x g

= 1 kg x 9.8m/s² =9.8 N

Discussion

678.	Write down the weight of a 50 kg mass on the earth, (g = 9.8 m/s2 ).
Answer» Weight, W= m x g =50 x 9.8=490N

Discussion

679.	A body has a weight of 10 kg on the surface of earth. What will be its weight when taken to the centre of the earth ?
Answer» Its weight will be zero as value of g is zero at the centre of the earth.

Discussion

680.	If the same body is taken to places having different gravitational ﬁeld strength, then what will vary: its weight or mass?
Answer» Correct Answer - Weight

Discussion

681.	If the same body is taken to places having different gravitational field strength, then what will vary: its weight or mass?
Answer» The weight of the body varies as the mass remains constant

Discussion

682.	Imagine a spacecraft going from the earth to the moon. How does its weight vary as it goes from earth to the moon?
Answer» As the spacecraft moves from the surface of the earth towards the moon. (i) its weight will start decreasing (ii) it becomes zero at the point where the force of attraction on the spacecraft due to the earth and the moon will just become equal and opposite and (iii) it will again start increasing as the spacecraft further moves towards the moon.

682.

Imagine a spacecraft going from the earth to the moon. How does its weight vary as it goes from earth to the moon?

Answer»

As the spacecraft moves from the surface of the earth towards the moon.

(i) its weight will start decreasing

(ii) it becomes zero at the point where the force of attraction on the spacecraft due to the earth and the moon will just become equal and opposite and

(iii) it will again start increasing as the spacecraft further moves towards the moon.

Discussion

683.	What is the weight of a 1kg mass of the earth? When g = 9.8 m/s2.
Answer» Weight, w = mg = (1) (9.8) = 9.8N

Discussion

684.	As the altitude of a body increases, do the weight and mass both vary?
Answer» the weight of the body varies with altitude whereas the mass of an object remains constant.

Discussion

685.	Can a body have weight but no mass?
Answer» No, weight=mg. If mass `m=0,w=0`, i.e., When mass is zero,weight is also zero.

Discussion

686.	If the mass of an object be 10 kg, what is its weight ? (g = 9.8 m/s2 ).
Answer» Weight, W = m x g = 10 x 9.8 =98 N

Discussion

687.	If the same body is taken to places having different gravitational field strength, then what will vary: its weight or mass ?
Answer» Its weight varies; mass of an object is constant.

Discussion

688.	If G is the uciversal gravitational constant and p is the uniform density of a spherical planet. Then shortest possible period o0f rotation around a planet can beA. `sqrt((piG)/(2p))`B. `sqrt((3piGP)/(p))`C. `sqrt((pi)/(6Gp))`D. `sqrt((3pi)/(Gp))`
Answer» Correct Answer - D

Discussion

689.	What does not change in the field of central forceA. Potential energyB. Kinetic energyC. Linear momentumD. Angular momentum
Answer» Correct Answer - D

Discussion

690.	A spherical uniform planet is rotating about its axis. The velocity of a point on its equator is `V`. Due to the rotation of planet about its axis the acceleration due to gravity `g` at equator is `1//2` of `g` at poles. The escape velocity of a particle on the planet in terms of `V`.A. `V_(e )=2V`B. `V_(e )=V`C. `V_(e )=V//2`D. `V_(e )=sqrt(3)V`
Answer» Correct Answer - A `g_(e )=g_(p)-R omega^(2) rArr (g)/(2)=g-R omega^(2)` `R omega^(2) = (g)/(2) rArr R^(2)omega^(2)=(gR)/(2) rArr V^(2)(gR)/(2)` ….(i) `V_(e ) = sqrt(2gR)` From (i) and (ii) `V_(e ) = sqrt(2xx2V^(2))rArr V_(e )=2V`

Discussion

691.	What is the mass of the planet that has a satellite whose time period is `T` and orbital radius is `r`?A. `4 pi^(2) R^(3)G^(-1)T^(-2)`B. `8pi^(2)R^(3)G^(-1) T^(-2)`C. `12 pi^(2) R^(3)G^(-1)T^(-2)`D. `16 pi^(2)R^(3)G^(-1) T^(-2)`
Answer» Correct Answer - A

Discussion

692.	If the orbital velocity of a planet is given by `v = G^(a) M^(b) R^(c )` thenA. `a=1//3, b=1//3, c= -1//3`B. `a=1//2, b=1//2, c= -1//2`C. `a=1//2, b= -1//2, c= 1//2`D. `a=1//2, b= -1//2, c= -1//2`
Answer» Correct Answer - B

Discussion

693.	The period of revolution of planet A round from the sun is 8 times that of B. The distance of A from the sun is how many times greater then tht of B from the sun ?A. 2B. 3C. 4D. 5
Answer» Correct Answer - c `T^(2)propR^(3)" "therefore (T_(1)^(2))/(T_(2)^(2))=(R_(1)^(3))/(R_(2)^(3))` `therefore " "(R_(1)^(3))/(R_(2)^(3))=64" "therefore" "R_(1)=4R_(2)`

Discussion

694.	The distance of geostationary satellite from the centre of the earth (radius R) is nearest toA. 5 RB. 6 RC. 7 RD. 8 R
Answer» Correct Answer - c The distance of the communication satellite from the centre of the earth is 7 R.

Discussion

695.	The radius of a planet is `1/4` of earth’s radius and its acceleration due to gravity is double that of earth’s acceleration due to gravity. How many times will the escape velocity at the planet’s surface be as compared to its value on earth’s surfaceA. `1/sqrt(2)`B. `sqrt(2)`C. `2sqrt(2)`D. `2`
Answer» Correct Answer - A

Discussion

696.	Write the answer of the following question in one word- (a) What is the orbital speed of Geo-stationary satellite ? (b) For a satellite moving in an orbit around the earth what is the ratio of kinetic energy to potential energy ?
Answer» Correct Answer - (a) 3.1 km/s; (b) `-1/2`

Discussion

697.	The radius of a planet is `1/4` of earth’s radius and its acceleration due to gravity is double that of earth’s acceleration due to gravity. How many times will the escape velocity at the planet’s surface be as compared to its value on earth’s surfaceA. `1//sqrt2`B. `sqrt2`C. `2//sqrt2`D. 2
Answer» Correct Answer - a `(v_(e_(2)))/(v_(e_(1)))=sqrt((g_(2))/(g_(1))xx(R_(2))/(R_(1)))=sqrt(2xx(1)/(4))=(1)/(sqrt2)` `(v_(e_(2)))/(v_(e_(1)))=(1)/(sqrt2)`

Discussion

698.	Critical velocity of the orbiting satellite is, independent ofA. mass of the satelliteB. redius of ciruclar orbitC. mass of the earth or planet from which satellite is projectedD. height of the satellite
Answer» Correct Answer - a

Discussion

699.	According to Kepler, the period of revolution of a planet ( T ) and its mean distance from the sun ( r ) are related by the equationA. `T^(2)r`= ConstantB. `T^(2)r^(-3)=` ConstantC. `T^(2)r^(3)="Constant"`D. `T^(3)r^(3)=` Constant
Answer» Correct Answer - b `T^(2)=(4pi^(2))/(GM)r^(3)` `(T^(2))/(T^(3))=(4pi^(2))/(GM)="constant"` `T^(2)r^(-3) = "constant."`

Discussion

700.	According to Kepler, the period of revolution of a planet ( T ) and its mean distance from the sun ( r ) are related by the equationA. `T^(2)r`= ConstantB. `T^(2)r^(-3)=` ConstantC. `Tr^(3)=` ConstantD. `T^(3)r^(3)=` Constant
Answer» Correct Answer - b

Discussion

Explore topic-wise InterviewSolutions in .

Write the formula to find the magnitude of the gravitational force between the Earth and an object on the surface of the Earth.

Choose the correct statement about gravitational forceA. It forms action-reaction pairB. It is a central forceC. It is a conservative forceD. It is independent of the medium between the masses

The correct graph representing the variation of total energy `(E_(t))`, kinetic energy `(E_(k))` and potential energy `(U)` of a satellite with its distance form the centre of earth isA. B. C. D.

The correct graph representing the variation of total energy `(E_(t))`, kinetic energy `(E_(k))` and potential energy `(U)` of a satellite with its distance form the centre of earth isA. B. C. D.

Identify the correct statementsA. The Earth always act like a point massB. To an apple, the Earth acts like a point massC. To a satellite, the Earth acts acts like point massD. To moon, the Earth acts like a point mass

A satellite is revolving in circular orbit of radius `r` around the earth of mass M. Time of revolution of satellite isA. `Tprop(r^(5))/(GM)`B. `T propsqrt((r^(3))/(GM))`C. `T prop sqrt((r)/((GM^(2))/(3)))`D. `T prop sqrt((r^(3))/((GM)/(4)))`

The period of a satellite moving in a circular orbit near the surface of a planet is independent ofA. mass of the planetB. radius of the planetC. mass of the satelliteD. density of planet

The period of a satellite in a circular orbit around a planet is independent ofA. the mass of the planetB. the radius of the planetC. the mass of the satelliteD. All the three parameters (a), (b) and (c)

The period of a satellite moving in a circular orbit near the surface of a planet is independent ofA. The mass of the planetB. The radius of the planetC. The mass of the satelliteD. All the three parameters (a), (b) and (c)

The period of a satellite moving in a circular orbit near the surface of a planet is independent ofA. radius of the planetB. mass of the planetC. mass of the satelliteD. none of the above

Time period of a satellite in a circular obbit around a planet is independent ofA. Radius of the orbitB. Mass of the planetC. Mass of the statelliteD. Radius of the planet

Orbital radius of a satellite S of earth is four times that s communication satellite C. Period of revolution of S is :-A. 4 daysB. 8 daysC. 16 daysD. 32 days

The period of revolution of an earth satellite close to surface of earth is 90min. The time period of aother satellite in an orbit at a distance of three times the radius of earth from its surface will beA. `90sqrt(8)min`B. `360min`C. `720min`D. `270min`

Three identical particles force exerted on one body due to the other two.

Which one of the following graphs represents correctly represent the variation of the gravitational field (E) with the distance (r) from the centre of a spherical shell of mass M radius R ?A. B. C. D.

Energy of a satellite in circular orbit is `E_(0)`. The energy required to move the satellite to a circular orbit of 3 times the radius of the initial orbit isA. `(2)/(3)E_(0)`B. `2E_(0)`C. `(E_(0))/(3)`D. `(3)/(2)E_(0)`

Four equal masses (each of mass M) are placed at the corners of a squares side a the escape velocity of a body from the centre O of the square isA. `4sqrt(2GM)/(a)`B. `sqrt(8sqrt(2GM))/(a)`C. `(4GM)/(a)`D. `sqrt(4sqrt(2)GM)/(a)`

The weight of a body at the centre of the earth isA. zeroB. infiniteC. same as no the surface of earthD. None of the above

The diagram showing the variation of gravitational potential of earth with distance from the centre of earth isA. B. C. D.

The correct variation of gravitational potential `V` with radius `r` measured from the centre of earth of radius `R` is given byA. B. C. D.

The relative densities of four liquids P,Q,R and S are 1.26,1.0,0.84, and 13.6 respectively .An object is floated in all these liquids ,one by one .In which liquid will is maximum volume submerged under the liquid ?A. PB. QC. RD. S

Two identical spheres are placed in contact with each other. The force of gravitation between the spheres will be proportional to ( R = radius of each sphere)A. RB. `R^(2)`C. `R^(4)`D. `1//R^(2)`

Two bodies of masses M and m are allowed to fall from the same height . If air resistance for each body be same , will the two bodies reach the ground simultaneously ?A. the ratio of the massesB. the inverse of the ratio of their massesC. oneD. product of their masses

What is the weight of a 1 kilogram mass on the earth? `(g = 9 .8 m//s^2).

What is the weight of a 1 kilogram mass on the earth ? (g = 9.8 m/s2 ).

Write down the weight of a 50 kg mass on the earth, (g = 9.8 m/s2 ).

A body has a weight of 10 kg on the surface of earth. What will be its weight when taken to the centre of the earth ?

If the same body is taken to places having different gravitational ﬁeld strength, then what will vary: its weight or mass?

If the same body is taken to places having different gravitational field strength, then what will vary: its weight or mass?

Imagine a spacecraft going from the earth to the moon. How does its weight vary as it goes from earth to the moon?

What is the weight of a 1kg mass of the earth? When g = 9.8 m/s2.

As the altitude of a body increases, do the weight and mass both vary?

Can a body have weight but no mass?

If the mass of an object be 10 kg, what is its weight ? (g = 9.8 m/s2 ).

If the same body is taken to places having different gravitational field strength, then what will vary: its weight or mass ?

If G is the uciversal gravitational constant and p is the uniform density of a spherical planet. Then shortest possible period o0f rotation around a planet can beA. `sqrt((piG)/(2p))`B. `sqrt((3piGP)/(p))`C. `sqrt((pi)/(6Gp))`D. `sqrt((3pi)/(Gp))`

What does not change in the field of central forceA. Potential energyB. Kinetic energyC. Linear momentumD. Angular momentum

What is the mass of the planet that has a satellite whose time period is `T` and orbital radius is `r`?A. `4 pi^(2) R^(3)G^(-1)T^(-2)`B. `8pi^(2)R^(3)G^(-1) T^(-2)`C. `12 pi^(2) R^(3)G^(-1)T^(-2)`D. `16 pi^(2)R^(3)G^(-1) T^(-2)`

If the orbital velocity of a planet is given by `v = G^(a) M^(b) R^(c )` thenA. `a=1//3, b=1//3, c= -1//3`B. `a=1//2, b=1//2, c= -1//2`C. `a=1//2, b= -1//2, c= 1//2`D. `a=1//2, b= -1//2, c= -1//2`

The period of revolution of planet A round from the sun is 8 times that of B. The distance of A from the sun is how many times greater then tht of B from the sun ?A. 2B. 3C. 4D. 5

The distance of geostationary satellite from the centre of the earth (radius R) is nearest toA. 5 RB. 6 RC. 7 RD. 8 R

Write the answer of the following question in one word- (a) What is the orbital speed of Geo-stationary satellite ? (b) For a satellite moving in an orbit around the earth what is the ratio of kinetic energy to potential energy ?

The radius of a planet is `1/4` of earth’s radius and its acceleration due to gravity is double that of earth’s acceleration due to gravity. How many times will the escape velocity at the planet’s surface be as compared to its value on earth’s surfaceA. `1//sqrt2`B. `sqrt2`C. `2//sqrt2`D. 2

Critical velocity of the orbiting satellite is, independent ofA. mass of the satelliteB. redius of ciruclar orbitC. mass of the earth or planet from which satellite is projectedD. height of the satellite

According to Kepler, the period of revolution of a planet ( T ) and its mean distance from the sun ( r ) are related by the equationA. `T^(2)r`= ConstantB. `T^(2)r^(-3)=` ConstantC. `T^(2)r^(3)="Constant"`D. `T^(3)r^(3)=` Constant

According to Kepler, the period of revolution of a planet ( T ) and its mean distance from the sun ( r ) are related by the equationA. `T^(2)r`= ConstantB. `T^(2)r^(-3)=` ConstantC. `Tr^(3)=` ConstantD. `T^(3)r^(3)=` Constant