General
✓✗Assertion: The value of g decreases as we go deep into the earth.
Reason: The mass of the earth that attracts a body decreases as it goes deeper, while its distance from the centre also decreases.
Reason: The mass of the earth that attracts a body decreases as it goes deeper, while its distance from the centre also decreases.
- Both Assertion and Reason are true and Reason is the correct explanation of Assertion
- Both Assertion and Reason are true but Reason is not the correct explanation of Assertion
- Assertion is true but Reason is false
- Both Assertion and Reason are false
General
✓✗According to Kepler's third law, the square of the period T of a planet is proportional to
- the semi-major axis
- the cube of the semi-major axis of its orbit
- the mass of the planet
- the square of the semi-major axis
General
✓✗The gravitational force on a body inside a uniform solid sphere, at a distance r from the centre, is directly proportional to
- 1/r
- r2
- 1/r2
- r
General
✓✗Two satellites of the earth, S1 and S2, are moving in the same orbit. The mass of S1 is four times the mass of S2. Which one of the following statements is true?
- The time period of S1 is four times that of S2.
- The kinetic energies of the two satellites are equal.
- S1 and S2 are moving with the same speed.
- The potential energies of the earth and satellite in the two cases are equal.
General
✓✗Gravitational force is a conservative force because
- the work done by it round any closed path is zero
- it is very weak
- it acts at a distance
- it is always attractive
General
✓✗The ratio of the energy needed to raise a satellite from the earth's surface to a height R to the energy needed to then put it into a circular orbit at that height is (R = earth's radius)
- 1 : 1
- 4 : 1
- 2 : 1
- 1 : 2
General
✓✗The period of a satellite in an orbit of radius 4R is T. The period of a satellite in an orbit of radius R is
- T/8
- T/4
- T/2
- 8T
General
✓✗The value of g on a planet is 25 m s−2. A body of mass 2 kg on it has a weight of
- 25 N
- 12.5 N
- 50 N
- 19.6 N
General
✓✗If the radius of the earth decreased by 1 % with its mass unchanged, the value of g on its surface would
- decrease by about 2 %
- increase by about 1 %
- remain unchanged
- increase by about 2 %
General
✓✗A body is weighed with a spring balance at the poles and at the equator. The reading is
- slightly larger at the equator
- zero at the equator
- the same at both places
- slightly larger at the poles
General
✓✗Match List I (quantity for a satellite in a circular orbit of radius r) with List II (dependence on r).
| List I | List II |
| P. Orbital speed | 1. r3/2 |
| Q. Period | 2. r−1/2 |
| R. Kinetic energy | 3. r1/2 |
| S. Angular momentum | 4. r−1 |
- P-2, Q-1, R-3, S-4
- P-4, Q-1, R-2, S-3
- P-2, Q-1, R-4, S-3
- P-3, Q-1, R-4, S-2
General
✓✗Two spheres of masses 10 kg and 20 kg have their centres 1 m apart. The gravitational force between them is about
- 200 N
- 1.33 × 10−11 N
- 1.33 × 10−8 N
- 6.67 × 10−11 N
General
✓✗A satellite in a circular orbit has total energy −E. Its kinetic energy is
- E
- −E
- E/2
- 2E
General
✓✗A satellite of mass m in a circular orbit of radius r around the earth (mass M) is moved to an orbit of radius 4r. The work done by the external agency is
- \( \dfrac{GMm}{8r} \)
- \( \dfrac{3GMm}{4r} \)
- \( \dfrac{GMm}{4r} \)
- \( \dfrac{3GMm}{8r} \)
General
✓✗A satellite A of mass m is at a distance r from the centre of the earth. Another satellite B of mass 2m is at a distance 2r from the earth's centre. Their time periods are in the ratio
- \( 1 : 2\sqrt2 \)
- 1 : 2
- 1 : 32
- 1 : 16