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Gravitation Class 11 MCQs Questions with Answers
Multiple Choice Type Questions
Question 1.
If the density of Earth is doubled keeping its radius constant then acceleration due to gravity will become (the present value is 9,8 ms-2)
(a) 9.8 ms-2
(b) 4.9 ms-2
(c) 19.6 ms-2
(d) 2.45 ms-2
Answer
Answer: (c) 19.6 ms-2
Question 2.
A satellite is orbiting around the Earth with a period T. If the Earth suddenly shrinks to half its radius without change in mass, the period of revolution of the satellite will be
(a) T
(b) \(\frac {T}{2}\)
(c) \(\frac {T}{√2}\)
(d) 2T
Answer
Answer: (a) T
Question 3.
Two satellites of mass m, and 10m, are put in the same orbit around the sun. If T1 and T2 be their time periods, then \(\frac {T_1}{T_2}\) =
(a) 4
(b) 1
(c) \(\frac {1}{2}\)
(d) \(\frac {1}{4}\)
Answer
Answer: (b) 1
Question 4.
A projectle is fired with a velocity less than the escape velocity. What can we say about the sum of its potential and kinetic energies?
(a) Negative
(b) Positive
(c) Zero
(d) May be +ve, -ve or zero
Answer
Answer: (a) Negative
Question 5.
The acceleration due to gravity’ increases by 0.5% when we go from equator to poles. What will be the time period of the pendulum at the equator which beats seconds at the poles?
(a) 1.950 s
(b) 1.995 s
(c) 2.050 s
(d) 2.005 s
Answer
Answer: (d) 2.005 s
Question 6.
At what height above the surface of Earth of radius R will the acceleration due to gravity be reduced by 0.1%?
(a) \(\frac {R}{100}\)
(b) \(\frac {R}{200}\)
(c) \(\frac {R}{1000}\)
(d) \(\frac {R}{2000}\)
Answer
Answer: (d) \(\frac {R}{2000}\)
Question 7.
A bail of weight W is thrown vertically upwards. The apparent w eight during the upward motion will be
(a) zero
(b) more than W
(c) less than W
(d) W
Answer
Answer: (a) zero
Question 8.
The acceleration due to gravity at a place is g. A ball of density ρ is gently released in a fluid of density σ. The downward acceleration of the ball if ρ > σ will be
(a) g
(b) g\(\frac {σ}{ρ}\)
(c) g(\(\frac {1-σ}{ρ}\))
(d) \(\sqrt{(1-\frac {ρ}{σ}})\)
Answer
Answer: (c) g(\(\frac {1-σ}{ρ}\))
Question 9.
The time period (T) of the artificial setelllite of Earth depends on the density (p) of the Earth as
(a) T ∝ r
(b) T ∝ \(\frac {1}{ρ}\)
(c) T ∝ \(\frac {1}{√ρ}\)
(d) T ∝ √ρ
Answer
Answer: (c) T ∝ \(\frac {1}{√ρ}\)
Question 10.
How much work per kilogram need to be done to shift a 1kg mass from the surface of Earth of infinity? Take acceleration due to gravity = g and radius of the Earth = R.
(a) gR
(b) \(\frac {R}{g}\)
(c) \(\frac {g}{R^2}\)
(d) \(\frac {g}{R}\)
Answer
Answer: (a) gR
Question 11.
What percentage of the potential energy is gained by the body in rising through a height equal to the radius of the Earth assuming that the gravitational potential energy of a body infinite distance away from Earth is zero.
(a) 1%
(b) 10%
(c) 50%
(d) 20%
Answer
Answer: (c) 50%
Question 12.
A person on the moon can jump higher than on the Earth as
(а) the moon has rough surface.
(b) the moon is cooler than Earth.
(c) the value of ‘g’ on the moon is smaller than that on the Earth.
(d) there is almost no atmosphere on the moon.
Answer
Answer: (c) the value of ‘g’ on the moon is smaller than that on the Earth.
Question 13.
The gravitational pull on two bodies is 6.67 × 10-11 Nm²kg-2 in vacuum. The value of the gravitational pull in a dense matter of density 1016 kg m-3 will be
(a) 6.67 × 10-11 Nm² kg-2
(b) 6.67 × 10-21 Nm² kg-2
(c) 1.3 × 10-10 Nm² kg-2
(d) 6.67 × 10-1 Nm² kg-2
Answer
Answer: (a) 6.67 × 10-11 Nm² kg-2
Question 14.
Which of the following is the evidence to show that there must be a force acting on Earth directed towards the Sun.
(a) revolution of Earth around the Sun.
(b) apparent motion of Sun around the Earth.
(c) duration of falling bodies towards Earth.
(d) phenomenon of day and night.
Answer
Answer: (a) revolution of Earth around the Sun.
Question 15.
In order to find the time, the astronaut orbiting in an Earth satellite should use:
(а) a pendulum clock.
(b) a watch having a hair spring to keep it going.
(c) either a pendulum clock or a watch.
(d) neither a pendulum clock nor a watch.
Answer
Answer: (b) a watch having a hair spring to keep it going.
Question 16.
The orbital speed of Jupiter is
(a) less than the orbital speed of Earth.
(b) greater than the orbital speed of Earth.
(c) equal to the orbital speed of Earth.
(d) zero.
Answer
Answer: (a) less than the orbital speed of Earth.
Question 17.
Weightlessness experienced while orbiting the earth in spaceship, is the result of:
(a) zero gravity
(b) centre of gravity
(c) inertia
(d) acceleration
Answer
Answer: (d) acceleration
Question 18.
The sky appears black to an astronaut in a spaceship. It is so because:
(a) surrounding medium absorbs sky light.
(b) the region has only invisible part (UV and IR) of Sun light.
(c) surrounding has no atmosphere.
(d) none of the above.
Answer
Answer: (c) surrounding has no atmosphere.
Question 19.
A satellite appears to be at rest when seen from the equator. Its height from the Earth’s surface is nearly
(a) 6400 km
(b) 32000 km
(c) 35800 km
(d) 358000 km
Answer
Answer: (c) 35800 km
Question 20.
The time period of a satellite revolving round the Earth at a height h from the Earth’s surface is given by
(a) 2π \(\sqrt{\frac {R^3}{GM}}\)
(b) 2π \(\sqrt{\frac {GM}{R^3}}\)
(c) 2π \(\sqrt {GMR^3}\)
(d) 2π \(\sqrt{\frac {(R+h)^3}{GM}}\)
Answer
Answer: (d) 2π \(\sqrt{\frac {(R+h)^3}{GM}}\)
Fill in the blanks
Question 1.
Two planets are at distances R1 and R2 from the Sun. Then the ratio of their period will be ………………..
Answer
Answer: (\(\frac {R_1}{R_2}\))³
Question 2.
If the Earth stops rotating about its axis, the value of gat the equator will increase by ……………….. where R is the radius of Earth and co is the angular velocity or rotation.
Answer
Answer: Rω².
Question 3.
If the Earth shrinks to half of its radius, its mass remaining the same, the weight of an object on Earth will increase ……………… times.
Answer
Answer: 4 times.
Question 4.
Let A be the area swept out by the line joining the Earth and Sun during February 2005. The area swept out by the line during a typical week in February 2005 is ………………….
Answer
Answer: \(\frac {A}{4}\)
Question 5.
The orbital velocity of the stationary satellite of Earth is nearly ……………..
Answer
Answer: 3 km s-1.
Question 6.
The orbit of a planet around the Sun is elliptical with Sun at one of its focii. The point closest to the Sun is called ………….. and the point farthest from the Sun is called ………………
Answer
Answer: Perihelion, Aphelion.
Question 7.
The escape velocity will ……………… if a planet is made bigger keeping its density constant.
Answer
Answer: Increase.
Question 8.
The orbital velocity of a satellite in an orbit depends upon the product of …………….. and ……………….
Answer
Answer: Acceleration due to gravity at that planet, radius of the planet.
Question 9.
…………….. is defined to be numerically equal to the force of attraction between two bodies each of mass 1kg and separated by a distance of 1 metre.
Answer
Answer: Universal gravitational constant (G).
Question 10.
Kepler’s 2nd law of motion which states that the radius vector of a planet from the Sun sweeps out equal area in equal intervals of time is a consequence of ……………….
Answer
Answer: Angular momentum.
True/False Type Questions
1. Tell which of the following statement is True/False for the given observation?
An iron and a cork ball of the same size are released from the same height in vacuum. Both of them reach the ground simultaneously. It is due to the following phenomenon:
(а) In vacuum, the acceleration due to gravity is zero.
(b) In vacuum, there is no resistance to the motion of the balls.
(c) Acceleration due to gravity in vacuum is independent of the size of the bodies.
(d) Acceleration due to gravity is independent of the mass of the falling bodies.
Answer
Answer:
(a) False
(b) False
(c) False
(d) True.
2. Tell which of the following statements will be True/False about the observation given here?
If the gravitational attraction of Earth suddenly disappears, then
(a) Both mass as well as the weight will be zero.
(b) Weight of the body will become zero but the mass will remain unchanged.
(c) Weight of the body will remain unchanged but the mass will become zero.
(d) Neither mass nor weight will be zero.
Answer
Answer:
(a) False
(b) True
(c) False
(d) False.
3. Tell which of the following statements are True/False about the variation of the gravitational field strength of Earth?
(a) The gravitational field strength increases when we go below the surface of Earth.
(b) Its magnitude is maximum at the surface of the Earth.
(c) It increases when we go above the surface of the Earth.
(d) “The moon is constantly falling towards Earth.”
Answer
Answer:
(a) False
(b) True
(c) False
(d) True.
4. Tell the True/False statement:
(a) The variation in the speed of the planets in their orbits about the Sun can be explained on the basis of the conservation of angular momentum. .
(b) Moon has no atmosphere because the escape velocity on it is small.
(c) A stationary satellite of a planet orbits at a definite height independent of its own mass.
(d) The time period of a satellite increases as radius of its orbit increases.
Answer
Answer:
(a) True
(b) True
(c) True
(d) True
5. Which of the following is True/False for a stationary satellite of the earth?
(a) It revolves from west to east.
(b) Its time period is 24 hours.
(c) It is stationary in space.
(d) Its angular speed is equal to that of Earth about its own axis.
Answer
Answer:
(a) True
(b) True
(c) False
(d) True
6. Which of the following statement is True/False about the satellite of Earth?
(a) It is weightless.
(b) It is freely falling.body.
(c) It is not accelerated.
(d) It has a constant speed.
Answer
Answer:
(a) True
(b) True
(c) False
(d) True.
7. Which of the following is True/False?
(a) G is a vector quantity.
(b) the weight of a body computed on the Earth is same during 24 hours of the day.
(c) The g will increase if a planet is made bigger keeping its density constant.
(d) The Earth moving around the sun in a circular orbit is acted on by a force and hence work must be done on the Earth by this force.
Answer
Answer:
(a) False
(b) True
(c) True
(d) False.
8. Tell which of the following statements are True/False?
(а) G is not equal to 6.67 × 10-11 Nm² kg-2 on the surface of Earth.
(b) The escape velocity on the surface of Earth is greater than the escape velocity from moon’s surface as moon has no atmosphere but Earth has.
(c) The angular momentum of a satellite going round the Earth remains conserved.
(d) The relation g= \(\frac {GM}{r^2}\)p holds good for all the celestial bodies.
Answer
Answer:
(a) False
(b) False
(c) True
(d) True.
9. Which of the following statements are True/False?
(a) A satellite going round the Earth suffers no acceleration.
(b) A heavier body fails faster than a lighter body under the force of gravity.
(c) The bodies in a uniform gravitational field experience gravitational force proportional to their masses.
(d) g is a scalar quantity.
Answer
Answer:
(a) False
(b) False
(c) True
(d) False.
10. Tell which of the following statements are True/False?
(a) A spaceship entering Earth’s atmosphere is likely to catch fire.
(b) ve > v0 for Earth.
(c) A surface at every point of which the gravitational potential remains same is called equipotential surface.
(d) g at pole is lesser than at the equator.
Answer
Answer:
(a) True
(b) True
(c) True
(d) False.
Match the following columns
Column I | Column II |
(a) The value of acceleration due to gravity (g) is maximum at | (i) the centre of Earth |
(b) The value of g is minimum at | (ii) poles |
(c) g is zero at | (iii) equator |
Answer
Answer:
Column I | Column II |
(a) The value of acceleration due to gravity (g) is maximum at | (ii) poles |
(b) The value of g is minimum at | (iii) equator |
(c) g is zero at | (i) the centre of Earth |
Column I | Column II |
(a) The centre of mass is called as the centre of gravity because | (i) becomes about 7.41 ms-2 |
(b) The value of g at a height of 1000 km from Earth’s surface | (ii) Torque due to gravity on a body about its centre of mass is zero |
(c) The moon’s height from Earth is | (iii) it does not depend on the nature of the medium between two objects and nature of bodies. |
(d) The G is called so because | (iv) 38 × 10-4 km. |
Answer
Answer:
Column I | Column II |
(a) The centre of mass is called as the centre of gravity because | (ii) Torque due to gravity on a body about its centre of mass is zero |
(b) The value of g at a height of 1000 km from Earth’s surface | (i) becomes about 7.41 ms-2 |
(c) The moon’s height from Earth is | (iv) 38 × 10-4 km. |
(d) The G is called so because | (iii) it does not depend on the nature of the medium between two objects and nature of bodies. |
Column I | Column II |
(a) Universal gravitational constant | (i) 9.8 ms-2 |
(b) Acceleration due to gravity on the surface of Earth | (ii) 1.63 ms-2 |
(c) Acceleration due to gravity on moon | (iii) 6.67 × 10-11 Nm²kg-2 |
Answer
Answer:
Column I | Column II |
(a) Universal gravitational constant | (iii) 6.67 × 10-11 Nm²kg-2 |
(b) Acceleration due to gravity on the surface of Earth | (i) 9.8 ms-2 |
(c) Acceleration due to gravity on moon | (ii) 1.63 ms-2 |
Column I | Column II |
(a) it is measured by studying the motion (acceleration) produced by the applied force. | (i) acceleration due to gravity |
(b) It is measured by studying the gravitationtel pull on it | (ii) inertial mass |
(c) It varies due to the shape of Earth | (iii) Gravitational mass |
Answer
Answer:
Column I | Column II |
(a) it is measured by studying the motion (acceleration) produced by the applied force. | (ii) inertial mass |
(b) It is measured by studying the gravitationtel pull on it | (iii) Gravitational mass |
(c) It varies due to the shape of Earth | (i) acceleration due to gravity |
Column I | Column II |
(а) The angle made by the line joining the point on earth’s surface to the centre of Earth with the equitorial plane | (i) 90° |
(b) Value of λ at pole | (ii) zero (0°) |
(c) Value of λ at equator | (iii) latitude at a point |
Answer
Answer:
Column I | Column II |
(а) The angle made by the line joining the point on earth’s surface to the centre of Earth with the equitorial plane | (iii) latitude at a point |
(b) Value of λ at pole | (i) 90° |
(c) Value of λ at equator | (ii) zero (0°) |
Column I | Column II |
(a) Difference between the value of g at pole and equator of Earth of radius 6.37 × 106 m is | (i) equal |
(b) Torque due to gravity on a body about its C.M. | (ii) 3.37 × 10-2 ms-2 |
(c) Earth’s attraction for 2kg of iron and attraction of 2kg of iron on Earth | (iii) zero |
Answer
Answer:
Column I | Column II |
(a) Difference between the value of g at pole and equator of Earth of radius 6.37 × 106 m is | (ii) 3.37 × 10-2 ms-2 |
(b) Torque due to gravity on a body about its C.M. | (iii) zero |
(c) Earth’s attraction for 2kg of iron and attraction of 2kg of iron on Earth | (i) equal |
Column I | Column II |
(a) Essential property of matter | (i) rotation of Earth |
(b) The value of ‘g’ does not change due to rotational motion of Earth | (ii) mass |
(c) The acceleration due to gravity decreases due to | (iii) at poles |
Answer
Answer:
Column I | Column II |
(a) Essential property of matter | (ii) mass |
(b) The value of ‘g’ does not change due to rotational motion of Earth | (iii) at poles |
(c) The acceleration due to gravity decreases due to | (i) rotation of Earth |
Column I | Column II |
(a) Orbital velocity of a satellite near Earth’s surface | (i) 2.38 kms-1 |
(b) Escape velocity on Earth’s surface | (ii) 7.92 kms-1 |
(c) Escape velocity at moon | (iii) 11.2 kms-1 |
Answer
Answer:
Column I | Column II |
(a) Orbital velocity of a satellite near Earth’s surface | (ii) 7.92 kms-1 |
(b) Escape velocity on Earth’s surface | (iii) 11.2 kms-1 |
(c) Escape velocity at moon | (i) 2.38 kms-1 |
Column I | Column II |
(a) It can never have a positive value | (i) Escape velocity |
(b) It does not depend upon the mass of the object to be projected | (ii) Gravitational potential |
(c) Potential energy of a galaxy is negative as | (iii) The forces between different galaxies are attractive in nature |
Answer
Answer:
Column I | Column II |
(a) It can never have a positive value | (ii) Gravitational potential |
(b) It does not depend upon the mass of the object to be projected | (i) Escape velocity |
(c) Potential energy of a galaxy is negative as | (iii) The forces between different galaxies are attractive in nature |
Column I | Column II |
(a) The acceleration due to gravity at a place is a measure of | (i) appear displaced away from the Sun |
(b) It is the shortest distance between two points | (ii) Gravitational field at that point |
(c) Due to gravitational field of sun the light from the star bend towards the sun so the stars | (iii) geodesic |
Answer
Answer:
Column I | Column II |
(a) The acceleration due to gravity at a place is a measure of | (ii) Gravitational field at that point |
(b) It is the shortest distance between two points | (iii) geodesic |
(c) Due to gravitational field of sun the light from the star bend towards the sun so the stars | (i) appear displaced away from the Sun |
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