Class 9 – Practice – Level 1 – Gravitation Leave a Comment / By Gulam Hamza / July 9, 2024 Class 9 - Practice - Level 1 - Gravitation Total questions: 40 1. Who formulated the Universal Law of Gravitation? Albert Einstein Isaac Newton Galileo Galilei Johannes Kepler None 2. The gravitational force between two objects depends on which of the following factors? Their masses The distance between them Both A and B Neither A nor B None 3. What is the value of the gravitational constant G? $ \displaystyle 6.67\times {{10}^{{-11}}}\,N{{m}^{2}}/k{{g}^{2}}$ $ \displaystyle 9.8\,m/{{s}^{2}}$ $ \displaystyle 3.14$ $ \displaystyle 1.6\times {{10}^{{-19}}}\,C$ None 4. What is the relation between weight and mass? Weight is mass times the acceleration due to gravity Weight is mass divided by the acceleration due to gravity Weight is independent of mass Weight is mass times velocity None 5. When an object is in free fall, the only force acting on it is: Air resistance Tension Gravitational force Friction None 6. What is the approximate value of acceleration due to gravity on the surface of the Earth? $ \displaystyle {9.8\,m/{{s}^{2}}}$ $ \displaystyle {6.67\times {{{10}}^{{-11}}}\,m/{{s}^{2}}}$ $ \displaystyle {1.6\times {{{10}}^{{-19}}}\,m/{{s}^{2}}}$ $ \displaystyle {3.14\,m/{{s}^{2}}}$ None 7. If the mass of an object is 10 kg, what is its weight on the surface of the Earth? 10 N 9.8 N 100 N 98 N None 8. Why do all objects fall at the same rate in a vacuum? Because there is no gravity in a vacuum Because there is no air resistance in a vacuum Because objects have no mass in a vacuum Because objects are weightless in a vacuum None 9. What is the gravitational potential energy of an object of mass 5 kg placed at a height of 10 meters above the ground? $ \displaystyle \left( {Use\text{ }g\text{ }=\text{ }9.8\,m/{{s}^{2}}} \right)$ 490 J 50 J 98 J 4900 J None 10. The point where the total mass of a body can be considered to be concentrated is called: Centre of gravity Centre of mass Centre of buoyancy Centre of pressure None 11. If the distance between two objects is doubled, the gravitational force between them becomes Four times Half Double One-fourth None 12. Astronauts feel weightless in a spacecraft orbiting the Earth because: There is no gravity in space The spacecraft is in free fall The gravitational force is very strong They are far from the Earth None 13. An object will float in a fluid if its density is: Greater than the density of the fluid Less than the density of the fluid Equal to the density of the fluid Independent of the density of the fluid None 14. According to Archimedes' Principle, the buoyant force on an object submerged in a fluid is equal to: The weight of the fluid displaced by the object The weight of the object The volume of the object The density of the fluid None 15. If a piece of wood has a mass of 50 grams and a volume of 100 cubic centimeters, what is its density? $ \displaystyle {0.5\text{ }g/cm{}^\text{3}}$ $ \displaystyle {1\text{ }g/cm{}^\text{3}}$ $ \displaystyle {2\text{ }g/cm{}^\text{3}}$ $\displaystyle {5\text{ }g/cm{}^\text{3}}$ None 16. The acceleration due to gravity on the Moon is approximately: $ \displaystyle {1.6\,m/{{s}^{2}}}$ $ \displaystyle {9.8\,m/{{s}^{2}}}$ $\displaystyle {3.7\,m/{{s}^{2}}}$ $ \displaystyle 24.8\,m/{{s}^{2}}$ None 17. A region in which a mass experiences a force due to gravitational attraction is called: Magnetic field Electric field Gravitational field Electromagnetic field None 18. The weight of an object is: The same everywhere More at the poles than at the equator Less at the poles than at the equator Independent of location None 19. The force with which the Earth attracts a body towards its center is called: Frictional force Centripetal force Gravitational force Electromagnetic force None 20. Why do astronauts appear to float in space? Because there is no gravity in space Because they are in a state of free fall Because they are weightless Because the spacecraft moves at a constant velocity None 21. The point where the gravitational force can be considered to act on an object is called: Centre of mass Centre of gravity Centre of buoyancy Centre of pressure None 22. Why does a feather fall slower than a stone in air? Because the feather has more mass Because the feather has more air resistance Because the stone is heavier Because the stone is denser None 23. The value of g decreases with: Increasing altitude Increasing depth Decreasing latitude Increasing latitude None 24. Artificial satellites orbit the Earth due to: Centripetal force Centrifugal force Gravitational force Electromagnetic force None 25. The condition in which objects appear to be weightless and float freely in a spacecraft is known as: Hypergravity Microgravity Zero gravity Reduced gravity None 26. Which of the following equations represents the gravitational force between two masses $ \displaystyle {{m}_{1}}\text{ }and\text{ }{{m}_{2}}$ separated by a distance r? $ \displaystyle F=G\frac{{{{m}_{1}}{{m}_{2}}}}{{{{r}^{2}}}}$ $ \displaystyle F\text{ }=G{{m}_{1}}{{m}_{2}}{{r}^{2}}$ $ \displaystyle F=G\frac{{{{m}_{1}}{{m}_{2}}}}{r}$ $ \displaystyle F=G\frac{{{{m}_{1}}{{m}_{2}}}}{{G{{r}^{2}}}}$ None 27. The Law of Universal Gravitation helps to explain which of the following phenomena? The motion of planets around the Sun The tides in the ocean The fall of an apple from a tree All of the above None 28. Which formula is used to calculate the gravitational potential energy of an object of mass mmm at a height h above the ground? $ \displaystyle {U\text{ }=\frac{1}{2}\text{ }mgh}$ $ \displaystyle {U\text{ }=\text{ }mgh}$ $\displaystyle {U\text{ }=\text{ }\frac{{mgh}}{2}\text{ }}$ $ \displaystyle {U\text{ }=\text{ }\frac{{mg}}{h}\text{ }}$ None 29. The inverse square law of gravitation states that the gravitational force between two objects is inversely proportional to the: Square of the distance between them Square of the sum of their masses Distance between them Product of their masses None 30. The speed at which a satellite must travel to stay in orbit around the Earth is called: Escape velocity Terminal velocity Orbital speed Gravitational speed None 31. The acceleration due to gravity is maximum at: The equator The poles The center of the Earth The surface of the Earth None 32. The minimum velocity required to escape Earth's gravitational field is known as: Terminal velocity Escape velocity Orbital velocity Gravitational velocity None 33. According to Newton's Law of Gravitation, if the mass of one object is doubled, the gravitational force between two objects will: Remain the same Double Halve Quadruple None 34. If a person weighs 60 kg on Earth, what would be their weight on the Moon? 50 N 20 N 60 N 10 N None 35. What are the units of the gravitational constant G? $\displaystyle {N{{m}^{2}}/k{{g}^{2}}}$ $ \displaystyle {m/{{s}^{2}}}$ $\displaystyle {kg/m}$ $ \displaystyle {m/N}$ None 36. If the distance between two masses is tripled, the gravitational force between them becomes One-ninth One-third Nine times Three times None 37. Objects in a freely falling lift are: Weightless Heavier Lighter Unaffected None 38. Which of the following is not one of Kepler's laws of planetary motion? Law of Orbits Law of Areas Law of Periods Law of Universal Gravitation None 39. Planets orbit the Sun in which shape according to Keplerâ€™s first law? Circular Elliptical Parabolic Hyperbolic None 40. Which of the following changes will increase the gravitational force between two objects? Increasing the distance between them Decreasing the distance between them Decreasing the masses of both objects Keeping the distance and masses constant None 1 out of 40 Time's up