CBSE Class 11 Physics Gravitation Assignment

Question. If the distance between two masses is doubled, the gravitational attraction between them:
a. Is doubled
b. Becomes four times
c. Is reduced to half
d. Is reduced to a quarter
Answer : D

Question. The earth (mass = 6×12⁴⁰ kg) revolves round the sun with angular velocity 2 x 10⁻⁷ rad/s in a circular orbit of radius 1.5×10⁸ km.The force exerted by the sun on the earth in newtons, is:
a. 18 ×10²⁵
b. Zero
c. 27 ×10³⁹
d. 36 ×10²¹
Answer : D
 

Question. The moon's radius is 1/4 that of the earth and its mass is 1/80 times that of the earth. If g represents the acceleration due to gravity on the surface of the earth that on the surface of the moon is:
a. g / 4
b. g / 5
c. g / 6
d. g / g
Answer : B

Question. The mass and diameter of a planet have twice the value of the corresponding parameters of earth. Acceleration due to gravity on the surface of the planet is:
a. 9.8m / sec²
b. 4.9 m / sec²
c. 980 m / sec²
d. 19.6 m / sec²
Answer : B

Question. If the radius of the earth were to shrink by 1% its mass remaining the same, the acceleration due to gravity on the earth's surface would:
a. Decrease by 2%
b. Remain unchanged
c. Increase by 2%
d. Increase by 1%
Answer : C

Question. The radii of two planets are respectively R₁ and R₂ and their densities are respectively ρ₁ and ρ₂ . The ratio of the accelerations due to gravity at their surfaces is:

Answer : D

Question. Where will it be profitable to purchase 1 kg sugar: (by spring balance)
a. At poles
b. At equator
c. At 45° latitude
d. At 40° latitude
Answer : B

Question. Four particles of masses m, 2m, 3m and 4m are kept in sequence at the corners of a square of side a. The magnitude of gravitational force acting on a particle of mass m placed at the centre of the square will be:
a. 24m²G /a²
b. 6m²G/a²
c. 4√2Gm²/a²
d. Zero
Answer : C

Question. 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: (both x and h being much smaller than the radius of the earth)
a. x = h
b. x = 2h
c.x = h/2
d. 2 x = h
Answer : B

Question. Weight of a body of mass m decreases by 1% when it is raised to height h above the earth's surface. If the body is taken to a depth h in a mine, change in its weight is:
a. 2% decrease
b. 0.5% decrease
c. 1% increase
d. 0.5% increase
Answer : B

Question. The depth d at which the value of acceleration due to gravity becomes 1/n times the value at the surface, is: [R = radius of the earth]
a. R/n
b. R(n − 1 / n)
c. R/n²
d. R(n/n+1)
Answer : B

Question. If the angular speed of earth is increased so much that the objects start flying from the equator, then the length of the day will be nearly:
a. 1.5 hours
b. 8 hours
c. 18 hours
d. 24 hours
Answer : A

Question. Knowing that mass of Moon is M/81 where M is the mass of Earth, find the distance of the point where gravitational field due to Earth and Moon cancel each other, from the Moon. Given that distance between Earth and Moon is 60 R. Where R is the radius of Earth:

a. 2 R
b. 4 R
c. 6 R
d. 8 R
Answer : C

Question. The intensity of gravitational field at a point situated at a distance of 8000 km from the centre of the earth is 6N/kg. The gravitational potential at that point is: (in Joule/ kg)
a. 8×10⁵
b. 2.4×10³
c. 4.8×10⁷
d. 6.4×10¹⁴
Answer : C

Question. The gravitational potential due to the earth at infinite distance from it is zero. Let the gravitational potential at a point P be −5J / kg . Suppose, we arbitrarily assume the gravitational potential at infinity to be + 10 J / kg , then the gravitational potential at P will be:
a. −5 J / kg
b. +5 J / kg
c. −15 J / kg
d. +15 J / kg
Answer : B

Question. Two bodies of masses m and M are placed a distance d apart. The gravitational potential at the position where the gravitational field due to them is zero is V, then:
a.V = - G/d (m + M)
b. V = - Gm/d
c. V = - GM/d
d. V = - G/d √(m + √M)
Answer : D

Question. If the earth suddenly shrinks (without changing mass) to half of its present radius, the acceleration due to gravity will be:
a. g/2
b. 4g
c. g/4
d. 2g
Answer : B

Question. Infinite bodies, each of mass 3kg are situated at distances 1m, 2m, 4m, 8m… respectively on x-axis. The resultant intensity of gravitational field at the origin will be:
a. G
b. 2 G
c. 3 G
d. 4 G
Answer : D

Question. If the distance between centres of earth and moon is D and the mass of earth is 81 times the mass of moon, then at what distance from centre of earth the gravitational force will be zero:
a. D/2
b. 2D/3
c. 4D/3
d. 9D/10
Answer : D

Question. Two concentric shells of mass M₁ and M₂ are having radii r₁ and r₂. Which of the following is the correct expression for the gravitational field on a mass m.

Answer : D

Question. At surface of earth weight of a person is 72 N then his weight at height R/2 from surface of earth is: (R = radius of earth)
a. 28 N
b. 16 N
c. 32 N
d. 72 N
Answer : C

Question. A uniform ring of mass m is lying at a distance 1.73 a from the centre of a sphere of mass M just over the sphere where a is the small radius of the ring as well as that of the sphere. Then gravitational force exerted is:

Answer : D

Question. The change in potential energy, when a body of mass m is raised to a height nR from the earth's surface is: (R = Radius of earth)
a. mgR (n / n - 1)
b. nmgR
c. mgR (n² / n² - 1)
d. mgR (n / n + 1)
Answer : D

Please refer to attached file for CBSE Class 11 Physics Gravitation Assignment