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Escape Velocity and Bound Systems

Questions covering escape velocity and bound systems, including calculations and theoretical applications. Suitable for physics exam preparation.

25 questions

What is the significance of the negative sign in the gravitational potential energy formula V\=−GMmr?

The negative sign indicates that gravitational potential energy is zero at infinite separation (r→∞) and decreases (becomes more negative) as objects approach each other. It reflects the attractive nature of gravity, where work must be done to separate masses.

Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.

Which of the following statements is correct about the gravitational force inside a hollow spherical shell?

The net gravitational force inside a uniform hollow spherical shell is zero due to symmetry, making option 2 correct. As per NCERT, applying relevant law/formula with correct units and sign convention leads to It is zero everywhere inside. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.

What is the total energy of a 100kg satellite orbiting Earth at 3RE from the center? (ME\=6×1024kg,RE\=6.4×106m,G\=6.67×

E = −GMEm2r. r = 3RE = 3×6.4×106 = 1.92×107m. E = −6.67×10−11×6×1024×1002×1.92×107. E = −4.002×10163.84×107≈−1.04×109J. As per NCERT, applying relevant law/formula with correct units and sign convention leads to -1.0 × 10⁹ J. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.

A moon orbits a planet with a period of 6 days and radius 4×108m. What is the planet’s mass? (G\=6.67×10−11N m2/kg2,1day

M = 4π2r3GT2. T = 6×86400 = 5.184×105s. T2 = 2.689×1011s2. r3 = (4×108)3 = 6.4×1025m3. M = 4×(3.14)2×6.4×10256.67×10−11×2.689×1011. M = 2.523×10261.794×101≈1.41×1025kg. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 1.4 × 10²⁵ kg. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.

A moon orbits a planet with a period of 11 days and radius 8×108m. What is the planet’s mass? (G\=6.67×10−11N m2/kg2,1da

M = 4π2r3GT2. T = 11×86400 = 9.504×105s. T2 = 9.028×1011s2. r3 = (8×108)3 = 5.12×1026m3. M = 4×(3.14)2×5.12×10266.67×10−11×9.028×1011. M = 2.019×10276.022×101≈3.35×1025kg. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 3.4 × 10²⁵ kg. This satisfies dimensional consistency and physical conditions given, so option C is scientifically correct.

Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.

A moon orbits a planet with a period of 12 days and radius 9×108m. What is the planet’s mass? (G\=6.67×10−11N m2/kg2,1da

M = 4π2r3GT2. T = 12×86400 = 1.0368×106s. T2 = 1.075×1012s2. r3 = (9×108)3 = 7.29×1026m3. M = 4×(3.14)2×7.29×10266.67×10−11×1.075×1012. M = 2.875×10277.171×101≈4.01×1025kg. As per NCERT, applying relevant law/formula with correct units and sign convention leads to 4.0 × 10²⁵ kg. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.

Why does the gravitational potential decrease (become less negative) as altitude increases?

As altitude increases, r (distance from Earth’s center) increases, reducing the magnitude of the negative term −GMmr, making V less negative. As per NCERT, applying relevant law/formula with correct units and sign convention leads to Distance from the center increases. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.

Why does a satellite in a higher orbit have a longer orbital period?

T2∝r3 for satellites. A higher orbit (larger r) increases T2 by r3, so the period T increases as the radius grows, reflecting weaker gravitational pull at greater distances. As per NCERT, applying relevant law/formula with correct units and sign convention leads to Gravitational force decreases. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.

What is the gravitational potential at a point 9.6×106m from Earth’s center due to Earth? ( ME\=6×1024kg,G\=6.67×10−11Nm

U = −GMEr. U = −6.67×10−11×6×10249.6×106. U = −4.002×10149.6×106 = −4.17×107J/kg. As per NCERT, applying relevant law/formula with correct units and sign convention leads to -4.2 × 10⁷ J/kg. This satisfies dimensional consistency and physical conditions given, so option B is scientifically correct.

Ref: Halliday & Resnick, Fundamentals of Physics, 11th ed., Chapter 13: Gravitation.