Gravitation Quiz - ICSE Class 11 Physics

Free practice quiz: Gravitation (ICSE Class 11 Physics). 51 multiple-choice questions with answers and explanations. Play online, no sign-up needed.

This ICSE Class 11 Physics practice quiz has 51 multiple-choice questions on Gravitation, and 51 of them come with an explanation. Try the 5 sample questions below (tap an option to check yourself), then play the full quiz online. No sign-up needed.

Sample questions

1. A satellite is orbiting the Earth in a circular orbit of radius R. If the satellite's speed is V, what is the force of gravity experienced by the satellite?

   1. mV²/R
   2. mR²/V
   3. mV/R²
   4. mR/V²
   Show answer

   Answer: A. mV²/R

   For a satellite in a circular orbit, the centripetal force required to maintain the orbit is provided by the force of gravity. The centripetal force is given by F = mV²/R, where m is the mass of the satellite, V is its orbital speed, and R is the radius of the orbit.

2. A planet has a mass twice that of Earth and a radius half that of Earth. What is the ratio of escape velocity from this planet to that from Earth?

   1. $\sqrt{2}$
   2. 2
   3. $2\sqrt{2}$
   4. 4
   Show answer

   Answer: C. $2\sqrt{2}$

   The escape velocity from the surface of a planet is given by $v_e = \sqrt{2GM/R}$. Let the Earth's mass be $M_E$ and radius be $R_E$. The escape velocity from Earth is $v_{eE} = \sqrt{2GM_E/R_E}$. For the new planet, its mass is $M_P = 2M_E$ and its radius is $R_P = R_E/2$. The escape velocity from this planet is $v_{eP} = \sqrt{2GM_P/R_P} = \sqrt{2G(2M_E)/(R_E/2)} = \sqrt{2G(4M_E)/R_E} = \sqrt{4} \sqrt{2GM_E/R_E} = 2 v_{eE}$. Wait, let me recheck the calculation. $v_{eP} = \sqrt{2G(2M_E)/(R_E/2)} = \sqrt{2G \cdot 2M_E \cdot (2/R_E)} = \sqrt{8 GM_E/R_E} = \sqrt{4} \sqrt{2GM_E/R_E} = 2 imes \sqrt{2} v_{eE}$. So the ratio $v_{eP}/v_{eE} = 2\sqrt{2}$. My previous calculation was incorrect. The correct answer is $2\sqrt{2}$.

3. A mass m is orbiting the Earth in a circular orbit of radius R. If the mass of the Earth doubles but the radius of the orbit remains the same, how does the orbital velocity change?

   1. Increases by a factor of $\sqrt{2}$
   2. Decreases by a factor of $\sqrt{2}$
   3. Doubles
   4. Halves
   Show answer

   Answer: A. Increases by a factor of $\sqrt{2}$

   For a satellite in a circular orbit, the orbital velocity v is given by $v = \sqrt{GM/R}$, where M is the mass of the planet and R is the radius of the orbit. If the mass of the Earth doubles (M becomes 2M) and the radius R remains the same, the new orbital velocity $v'$ will be $v' = \sqrt{G(2M)/R} = \sqrt{2} \sqrt{GM/R} = \sqrt{2} v$. Therefore, the orbital velocity increases by a factor of $\sqrt{2}$.

4. A satellite of mass m is in a circular orbit of radius r around a planet of mass M. What is the magnitude of the gravitational force acting on the satellite?

   1. $G M m / r$
   2. $G M m / r^2$
   3. $G m / r^2$
   4. $G M / r^2$
   Show answer

   Answer: B. $G M m / r^2$

   Newton's law of universal gravitation states that the force of gravity between two objects of masses M and m separated by a distance r is given by $F = G \frac{M m}{r^2}$. In this case, M is the mass of the planet, m is the mass of the satellite, and r is the radius of the orbit (distance between their centers).

5. A meteoroid is falling towards the Earth. As it enters the Earth's atmosphere, its speed increases significantly due to air resistance and gravitational acceleration. What is the primary reason for its initial acceleration towards Earth?

   1. Centrifugal force
   2. Gravitational force
   3. Centripetal force
   4. Inertial force
   Show answer

   Answer: B. Gravitational force

   The primary force causing the meteoroid to accelerate towards the Earth is the Earth's gravitational pull. Air resistance acts as a retarding force, opposing motion, and while it can affect the speed, the initial and sustained acceleration towards Earth is due to gravity.

More questions in this quiz

Answers and explanations are in the full quiz.

1. The escape velocity from the surface of the Earth is approximately 11.2 km/s. What is the escape velocity from a planet with twice the mass and the same radius as Earth?
2. Two stars of masses M and 4M are separated by a distance d. At what point between them will the gravitational force on a third body be zero?
3. A geostationary satellite orbits the Earth in a circular path. Which of the following statements is true about its motion?
4. The gravitational potential energy of a body of mass m at a distance r from the center of the Earth is given by -GMm/r. What is the work done by the gravitational force when the body moves from infinity to a distance r from the Earth's center?
5. A planet has twice the mass and half the radius of the Earth. How does the acceleration due to gravity on its surface compare to that of Earth?
6. The orbital period of a satellite in a circular orbit around the Earth is T. If the radius of the orbit is increased by a factor of 8, what will be the new orbital period?
7. What is the gravitational potential energy of a system of two particles of masses m and M separated by a distance r?
8. A body is projected vertically upwards with a velocity $v_0$. What is the ratio of its kinetic energy at the highest point to its kinetic energy at the point of projection, assuming no air resistance?
9. If the Earth suddenly stops rotating, what would be the change in the acceleration due to gravity at the equator?
10. Which of the following statements about gravitational waves is INCORRECT?
11. A satellite is in a circular orbit of radius R around a planet. If the satellite's kinetic energy is K, what is its total mechanical energy?
12. The gravitational force between two point masses is F. If the distance between them is doubled, what will be the new gravitational force?
13. A body of mass m is at a distance R from the center of a planet of mass M. If the body is moved closer to the planet such that its distance becomes R/2, what is the change in its gravitational potential energy?
14. Consider a binary star system where two stars of equal mass M orbit their common center of mass. If the distance between them is d, what is the orbital speed of each star?
15. A rocket is launched from the Earth's surface. At what altitude above the Earth's surface will the acceleration due to gravity be 1/4th of its value at the surface?
16. The Earth is approximately a sphere. If the Earth's mass were to increase by 10% while its radius remained the same, by what percentage would the acceleration due to gravity at its surface change?
17. A satellite is in a circular orbit around a planet. If its speed were to increase by 10%, what would happen to its orbit?
18. What is the gravitational pull experienced by a 1 kg mass at a distance of 1 meter from the center of the Earth (Mass of Earth = $6 imes 10^{24}$ kg, Radius of Earth = $6.4 imes 10^6$ m, G = $6.67 imes 10^{-11} \, Nm^2/kg^2$)?
19. What is the SI unit of gravitational potential energy?
20. A projectile is launched from the surface of the Earth with a velocity equal to escape velocity. What will be its trajectory?
21. What is the gravitational force between two neutrons if they are 1 meter apart? (Mass of neutron $\approx 1.67 imes 10^{-27}$ kg, G = $6.67 imes 10^{-11} \, Nm^2/kg^2$)
22. What is the unit of Gravitational Constant G?
23. If a planet has a density $ ho$ and radius R, what is the acceleration due to gravity on its surface?
24. A body is taken from the surface of the Earth to a height equal to the radius of the Earth. How does its weight change?
25. What is the condition for a particle to move in a circular orbit around a celestial body?
26. If the Earth were to shrink to half its radius while its mass remained constant, what would be the acceleration due to gravity at its surface?
27. Which of the following statements is incorrect regarding gravitational lensing?
28. The escape velocity from the surface of a planet is $v_e$. If the planet's radius is doubled while its mass remains constant, what is the new escape velocity?
29. A body is projected vertically upwards with a velocity $v$. At what height will its kinetic energy be half of its initial kinetic energy?
30. The gravitational potential energy of a particle of mass m at a distance r from the center of the Earth is $U(r) = -GMm/r$. What is the gravitational force on the particle?
31. A satellite orbits the Earth in an elliptical path. Its speed is highest when it is:
32. If the Earth were to have twice its current mass and half its current radius, how would its escape velocity change?
33. A body of mass m is on the surface of a planet of mass M and radius R. What is the orbital speed required for the body to be in a circular orbit at the surface?
34. The gravitational field strength at a point is defined as:
35. What is the value of the gravitational constant G?
36. If the Earth's mass were compressed into a smaller radius, what would happen to the escape velocity from its surface?
37. Two bodies of mass $m_1$ and $m_2$ are at a distance r. If both masses are doubled, how does the gravitational force between them change?
38. The gravitational potential at a point is defined as:
39. A spaceship is in a circular orbit around the Moon. If it fires its engines to increase its speed, what will happen to its orbit?
40. The weight of an object on the Moon is approximately 1/6th of its weight on Earth. This is because:
41. What is the total mechanical energy of a satellite in a circular orbit of radius r with speed v?
42. If the radius of the Earth suddenly reduced to half of its present value, while its mass remained the same, the acceleration due to gravity at the surface would be:
43. Which of the following is a consequence of the universality of gravitational force?
44. The gravitational potential energy of a system of particles is zero when:
45. A small satellite is in a circular orbit around a planet. If the satellite's velocity is increased such that it is now moving with twice its previous speed, what will be the shape of its new orbit?
46. What is the condition for a satellite to be in geostationary orbit?

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