CBSE Class 9 Science Gravitation MCQs Set D

Question: The value of G was first determined experimentally by
a) Newton
b) Henry Cavendish
c) Kepler 
d) Galileo 
Answer: c

Question: Where will it be profitable to purchase one kilogram of apples?
a) At poles
b) At equator
c) At 45° latitudes
d) at 60° latitude
Answer: b

Question: The acceleration due to gravity
a) has the same value everywhere in space.
b) has the same value everywhere on the earth.
c) varies with the latitude on the earth.
d) is greater on the moon.
Answer: c

Question: A ball is dropped from a spacecraft revolving around the earth at a height of 120 km. What will happen to the ball
a) It will continue to move with velocity v along the original orbit of spacecraft
b) It will move with the same speed tangentially to the spacecraft
c) It will fall down to the earth gradually
d) It will go very far in the space
Answer: a

Question: Particles of masses 2M, m and M are respectively at points A, B and C with AB = 1/2(BC). m is much-much smaller than M and at time t = 0, they are all at rest. At subsequent times before any collision takes place 

a) m will remain at rest.
b) m will move towards M.
c) m will move towards 2M.
d) m will have oscillatory motion. 
Answer: c

Question: Which is wrong statement about acceleration due to gravity?
a) Its value is 9.8 m/s²
b) It is zero at the centre of the earth.
c) Its value changes from place to place.
d) It is a scalar quantity.
Answer: d

Question: Acceleration due to gravity on the moon is of that on the earth.
a) 1/6th
b) 1/3rd
c) 1/4th
d) 1/5th
Answer: a

Question: Two identical satellites are at R and 7R away from earth surface, the wrong statement is (R = Radius of earth)
a) Ratio of total energy will be 4
b) Ratio of kinetic energies will be 4
c) Ratio of potential energies will be 4
d) Ratio of total energy will be 4 but ratio of potential and kinetic energies will be 2
Answer: d

Question: The mass of a body is increased 4 fold and mass of other body is increased 16 fold) How should the distance between them be changed to keep the same gravitational force between them?
a) 4 times
b)1/4 times
c) 8 times
d) 1/8 times 
Answer: c

Question: An astronaut in the orbit in a spacecraft feels weightlessness
a) due to the absence of gravity inside
b) due to the fact that spacecraft has no energy
c) because acceleration in the orbit is equal to acceleration of gravity outside
d) there is no gravity outside
Answer: c

Question: The value of universal gravitational constant was first determined experimentally by
a) Newton.
b) Galileo.
c) Cavendish.
d) Einstein.
Answer: c

Question: When a body is dropped from a certain height, acceleration due to gravity is taken as
a) + 9.8 m/s²
b) –9.8 m/s²
c) 0
d) + 9.8 m/s
Answer: a

Question: The gravitational force of attraction between the earth and the moon is
a) 2.22 × 10²⁰ N
b) 2.02 × 10²⁰ N
c) 2.02 × 10¹⁰ N
d) 3.02 × 10²⁰ N
Answer: b

Question: When the distance between the two objects is reduced to half, the force of gravitation becomes of the initial value.
a) ½
b) thrice
c) ¼
d) 4 times
Answer: d

Question: The accepted value of G is
a) 6.674 × 10^–11 Nm²/kg²
b) 5.674 × 10^–11 Nm²/kg²
c) 6.674 × 10^–10 Nm²/kg²
d) 6.674 × 10^–11 Nm²/kg
Answer: a

Question: An artificial satellite is placed into a circular orbit around earth at such a height that it always remains above a definite place on the surface of earth. Its height from the surface of earth is 
a) 6400 km
b) 4800 km
c) 32000 km
d) 36000 km
Answer: d

Question: Two planets A and B of same mass and same radius are shown in the figure. p₁ and p₂ are densities of the materials in the planets and p₁ > p₂. If the accelerations due to gravity on the surfaces of the planets A and B are gA and gB respectively, then

a) g_A = g_B
b) g_A < g_B
c) g_A > g_B 
d) Given information is not sufficient
Answer: a

Question: The equation F = Gm₁m₂/r² is valid for
a) rectangular bodies
b) circular bodies
c) elliptical bodies
d) spherical bodies
Answer: d

Question: The orbital velocity of a planet revolving close to earth's surface is 
a) √2gR
b) √gR
c) √2g/R
d) √g/R
Answer: b

Question: When the masses of two objects are doubled, the force of gravitation between them becomes the original value.
a) 4 times
b) double
c) 5 times
d) 8 times
Answer: a

Question: Two satellites A and B go round a planet P in circular orbits having radii 4R and R respectively. If the speed of the satellite A is 3V, the speed of the satellite B will be.
a) 12 V
b) 6 V
c) 4/3 V
d) 3/2 V
Answer: b

Question: If g₀, g_h and g_d be the acceleration due to gravity at earth’s surface, at height h and at a depth d respectively, then
a) g0 > gh and g0 > gd
b) g0 < gh and g0 < gd
c) g0 > gh and g0 < gd
d) g0 < gh and g0 > gd
Answer: a

Question: A satellite moves round the earth in a circular orbit of radius R making one revolution per day. A second satellite moving in a circular orbit, moves round the earth once in 8 days. The radius of the orbit of the second satellite is
a) 8 R
b) 4R
c) 2R
d) R
Answer: b

Question: If satellite is shifted towards the earth. Then time period of satellite will be 
a) Increase
b) Decrease
c) Unchanged
d) Nothing can be said 
Answer: b

Question: 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 
a) Zero
b) 23LGM
c) 29LGM
d) 2312LGM
Answer: a

Question: Given radius of Earth ‘R’ and length of a day ‘T’ the height of a geostationary satellite is [G–Gravitational Constant, M–Mass of Earth] 

Answer: c

Question: If R is the radius of the earth, the height at which the weight of a body becomes ¼ its weight on the surface of the earth is
a) 2R
b) R
c) R/2
d) R/4
Answer: b

Question: When the distance between the two objects is doubled, the force of gravitation becomes of the initial value.
a) 4 times
b) ¼
c) double
d) ½
Answer: b

Question: The time period of a satellite of earth is 5 hours. If the separation between the earth and the satellite is increased to four times the previous value, the new time period will become
a) 20 hours
b) 10 hours
c) 80 hours
d) 40 hours
Answer: d

 Question: Which of the following statements is/are correct?
I. Mass of an object is the measure of its inertia
II. Heavier the object smaller is the inertia
III. The mass of an object is variable.
a) Only I
b) I and III
c) II and III
d) I and II 
Answer: a