CBSE Class 9 Science Gravitation MCQs Set C

Question: Newton’s law of gravitation is valid
a) on the earth only
b) on the moon only
c) in the laboratory only
d) everywhere
Answer: d

Question: Which of the following is correct for mass?
a) It is a vector quantity.
b) It is not a fundamental property of material body.
c) It is the force with which the earth attracts a body.
d) It is the quantity of matter contained in a body. 
Answer: d

Question: When an object is thrown upward, the force of gravity is
a) opposite to the direction of motion
b) in the same direction as the direction of motion
c) becomes zero at the highest point
d) increases as it rises up. 
Answer: a

Question: What happens to the acceleration due to gravity with the increase in altitude from the surface of the earth?
a) Increases
b) Decreases
c) First decreases and then increases
d) Remains same
Answer: b

Question: Distance of geostationary satellite from the surface of earth radius(R_e = 6400 km) in terms of R_e is
a) 13.76 R_e
b) 10.76 R_e
c) 6.56 R_e
d) 2.56 R_e
Answer: c

Question: According to Kepler’s law the relationship between T (time period of revolution of a planet) and r (the semi-major axis of ellipse) is
a) T² ∝ r
b) T² ∝ r²
c) T² ∝ r^–3
d) T ∝ r^3/2
Answer: d

Question: Average distance of the earth from the sun is L₁. If one year of the earth = D days, one year of another planet whose average distance from the sun is L₂ will be 

Answer: b

Question: When a body is thrown up, the force of gravity is
a) in the upward direction
b) in the downward direction
c) zero
d) in the horizontal direction
Answer: b

Question: Newton’s law of gravitation is valid
a) in laboratory
b) only on the earth
c) only in our solar system
d) everywhere
Answer: d

Question: Gravitational force is a
a) repulsive force.
b) attractive force.
c) neither repulsive force. nor attractive force.
d) both repulsive force. and attractive force.
Answer: b

Question: Acceleration due to gravity on the moon is
a) 9.8 m/s²
b) 1.63 m/s²
c) 1.67 m/s²
d) 1.66 m/s²
Answer: b

Question: The point where the pull of the earth exerting on a body is equal to the pull exerted by the moon is called
a) zero gravity.
b) null point.
c) gravitational constant.
d) escape point.
Answer: b

Question: An apple falls towards the earth because the earth attracts it. The apple also attracts the earth by the same force. Why do we not see the earth rising towards the apple?
a) Acceleration of the earth is very large when compared to that of apple.
b) Acceleration of the earth is equal to that of apple.
c) Acceleration of the earth is neither high nor too low.
d) Acceleration of the earth is very small when compared to that of apple. 
Answer: d

Question: According to one of the Kepler’s laws of planetary motion
a) r² ∝ T³
b) r ∝ T²
c) r³ ∝ T²
d) r³ ∝ 1/T³
Answer: c

Question: A person in a spaceship moving in space, experience weightlessness as the value of 
a) mass is zero
b) acceleration due to gravity is zero
c) gravitational force is zero
d) none of these
Answer: b

Question: When an object is thrown upward, the force of gravity is
a) opposite to the direction of motion
b) in the same direction as the direction of motion
c) becomes zero at the highest point
d) increases as it rises up
Answer: a

Question: The value of acceleration due to gravity of earth
a) is the same on equator and poles.
b) is the least on poles.
c) is the least on equator.
d) increases from pole to equator.
Answer: c

Question: The statement “All bodies whether light or heavy, fall at the same speed towards the earth” was proposed by
a) Newton.
b) Cavendish.
c) Kepler.
d) Galileo.
Answer: d

Question: Value of acceleration due to gravity at the centre of the earth is
a) > 0
b) < 0
c) 9.8 m/s²
d) 0
Answer: d

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: Which law is it – “A planet revolves around the sun in an elliptical orbit”?
a) Newton’s first law
b) Newton’s second law
c) Kepler’s first law
d) Kepler’s second law
Answer: c

Question: Inverse square law is also called
a) Kepler’s first law.
b) Newton’s second law.
c) Universal law.
d) Gravitational law.
Answer: c

Question: Two satellite A and B, ratio of masses 3 : 1 are in circular orbits of radii r and 4r. Then ratio of total mechanical energy of A to B is 
a) 1 : 3
b) 3 : 1
c) 3 : 4
d) 12 : 1
Answer: d

Question: The weight of a body of mass 5 kg is
a) 69.0 N
b) 79.0 N
c) 49.0 N
d) 39.0 N 
Answer: c

Question: The value of acceleration due to gravity is high if
a) mass and radius both are small
b) mass is small and radius is large
c) mass is large and radius is small
d) mass and radius both are large. 
Answer: c

Question: A physical balance is used to measure the of an object.
a) weight
b) acceleration
c) mass
d) density
Answer: c

Question: A geo-stationary satellite is orbiting the earth at a height of 6 R above the surface of earth, R being the radius of earth. The time period of another satellite at a height of 2.5 R from the surface of earth is
a) 10 hr
b) (6/√2)hr
c) 6 hr
d) 6 2 hr
Answer: d

Question: The weight of a body of mass 10 kg is
a) 98 N
b) 9.8 N
c) 69 N
d) 39 N
Answer: a

Question: Which is not a vector quantity?
a) mass
b) weight
c) force
d) acceleration
Answer: a

Question: The weight of a man on the moon if he weighs 54 N on the earth is
a) 5.4 N
b) 54 N
c) 9 N
d) 324 N
Answer: c

Question: When the distance between two objects is tripled, the force of gravitation becomes of its initial value.
a) 1/4th
b) 1/7th
c) 1/8th
d) 1/9th
Answer: d

Question: Which of the following statements is correct in respect of a geostationary satellite 
a) It moves in a plane containing the Greenwich meridian
b) It moves in a plane perpendicular to the celestial equatorial plane
c) Its height above the earth’s surface is about the same as the radius of the earth
d) Its height above the earth’s surface is about six times the radius of the earth
Answer: d

Question: Which is a wrong statement about universal gravitational constant?
a) It has the same value at all places.
b) It is never zero.
c) It is vector quantity.
d) It value is 6.67 × 10^–11 Nm²/kg²
Answer: c

Question: The formation of tides in the sea is due to
a) the gravitational pull of the earth on sea water.
b) gravitational force exerted by the sun on the sea water.
c) gravitational force exerted by the moon on sea water.
d) gravitational force exerted by the moon and the sea on sea water.
Answer: d

Question: When you put an object on a spring balance, you measure
a) mass.
b) force.
c) acceleration.
d) weight.
Answer: d

Question: A satellite is launched into a circular orbit of radius ‘R’ around earth while a second satellite is launched into an orbit of radius 1.02 R. The percentage difference in the time periods of the two satellites is
a) 0.7
b) 1.0
c) 1.5
d) 3
Answer: d

Question: For a satellite escape velocity is 11 km/s. If the satellite is launched at an angle of 60° with the vertical, then escape velocity will be 
a) 11 km/s
b) 11 √3 km/s
c) 11/√3 km/s
d) 33 km/s
Answer: a

Question: A stone is allowed to fall from the top of a tower 100 m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25 m/s. Calculate when the two stones will meet.
a) 4 s
b) 3.6 s
c) 2 s
d) 8 s 
Answer: a

Question: Gravitational force is the
a) strongest force.
b) weakest force.
c) short-range force.
d) non-central force.
Answer: b

Question: If g_e is acceleration due to gravity on earth and g_m is acceleration due to gravity on moon, then
a) g_e = g_m
b) g_e < g_m
c) g_e = 1/6 g_m
d) g_e = 1/6 g_m 
Answer: d