Question 21 : A missile is launched with a velocity less than the escape velocity. The sum of its kinetic and potential energy is
1. Positive
2. Negative
3. may be positive or negative
4. Zero
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Question 22 : If the earth is 1/4th of its present distance from the sun, the duration of the year would be
1. 1/4 of the present year
2. 1/6 of the present year
3. 1/8 of the present year
4. 1/16 of the present year
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Question 23 : If the gravitational force between two objects were proportional to 1/R (and not as 1/R2) where R is separation between them, then a particle in circular orbit under such a force would have its orbital speed v proportional to
1. R⁰
2. 1/R²
3. R
4. 1/R
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Question 24 : The period of a satellite in a circular orbit of radius R is T. The period of another satellite in circular orbit of radius 4R is
1. T/4
2. 8T
3. 2T
4. T/8
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Question 25 : Kepler's second law regarding constancy of arial velocity of a planet is a consequence of the law of conservation of
1. angular momentum
2. energy
3. none of these
4. linear momentum
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Question 26 : A thief stole a box with valuable article of weight 'W' and jumped down a wall of height h. Before he reach the ground he experienced a load o
1. zero
2. W / 2
3. W
4. 2 W
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Question 27 : The ratio of the time periods for two satellites of equal mass in circular orbits of radii R and 9 R is
1. 1:27
2. 27:01:00
3. 9:01
4. 1:09
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Question 28 : A planet is moving around the Sun in a circular orbit of circumference C. The work done on the planet by the gravitational force F of the Sun is
1. F/C
2. FC
3. Zero
4. FC/2
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Question 29 : If the radius of the Earth were increased by a factor of 4 and its mass remained the same, then the acceleration due to gravity on the Earth would
1. increase by a factor of 16
2. increase by a factor of 4
3. reduce by a factor of 16
4. reduce by a factor of 4
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Question 30 : If the value of gravitational acceleration at a height h above the Earth's surface is the same as that at a depth d below the Earth's surface (with both h and d small compared to the Earth's radius R), then
1. h = d² / R
2. h = d / 2
3. h = d
4. h = 2 d
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