Class 9 – Practice Level 2 – Gravitation set – 2 Leave a Comment / By anushka kumari / July 9, 2024 Class 9 - Practice Level 2 – Gravitation set - 2 Total questions: 25 1. Calculate the gravitational force between two 20 kg masses separated by a distance of 3 meters. $ \displaystyle (Use G=6.67\times {{10}^{{-11}}}N{{m}^{2}}/k{{g}^{2}})$ $ \displaystyle \mathbf{Gravitational}\text{ }\mathbf{force}:2.97\times {{10}^{{-9}}}N$ $ \displaystyle \mathbf{Gravitational}\text{ }\mathbf{force}:8.89\times {{10}^{{-10}}}N$ $ \displaystyle \mathbf{Gravitational}\text{ }\mathbf{force}:1.48\times {{10}^{{-10}}}N$ $ \displaystyle \mathbf{Gravitational}\text{ }\mathbf{force}:2.97\times {{10}^{{-10}}}N$ None 2. If a person weighs 800 N on Earth, what would be their weight on Venus where the acceleration due to gravity is $ \displaystyle 8.87m/{{s}^{2}}$ Weight: 724 N Weight: 762 N Weight: 774 N Weight: 816 N None 3. Calculate the gravitational potential energy of a 5 kg mass at a height of 10 meters above the ground$ \displaystyle {(\text{Use }g=9.8m/{{s}^{2}})}$ Potential energy: 490 J Potential energy: 980 J Potential energy: 1470 J Potential energy: 1960 J None 4. An object is dropped from a height of 45 meters. Assuming no air resistance, what will be its velocity just before it hits the ground? $ \displaystyle {(\text{Use }g=9.8m/{{s}^{2}})}$ Velocity: 20.1 m/s Velocity: 25.3 m/s Velocity: 29.7 m/s Velocity: 30.0 m/s None 5. If the distance between two masses is quadrupled, how does the gravitational force between them change? It becomes one-sixteenth It becomes one-fourth It becomes four times It becomes sixteen times None 6. How does the value of g change as you move from the equator to the poles? It increases It decreases It remains constant It first increases then decreases None 7. Calculate the escape velocity from the surface of Mars where the radius of Mars is $ \displaystyle \text{3}\text{.39}\times \text{1}{{\text{0}}^{6}}\text{ and }g=3.71m/s$ Escape velocity: 5.0 km/s Escape velocity: 7.0 km/s Escape velocity: 9.0 km/s Escape velocity: 11.0 km/s None 8. Calculate the orbital speed of a satellite orbiting the Earth at an altitude of 400 km. $ \displaystyle \left( {\text{Radius of Earth R}=6400km,g=9.8m/{{s}^{2}}} \right)$ Orbital speed: 7.5 km/s Orbital speed: 7.8 km/s Orbital speed: 8.1 km/s Orbital speed: 8.4 km/s None 9. If an object is raised to a height twice its original height, how does its gravitational potential energy change? It remains the same It doubles It triples It quadruples None 10. How does the mass of an object affect its weight? Weight is independent of mass Weight is directly proportional to mass Weight is inversely proportional to mass Weight is equal to mass None 11. What is the gravitational field strength at a point 1000 km above the Earth's surface? $ \displaystyle \left( {\text{Radius of Earth R}=6400km,g=9.8m/{{s}^{2}}} \right)$ Field strength: 7.3 N/kg Field strength: 8.2 N/kg Field strength: 8.6 N/kg Field strength: 9.0 N/kg None 12. How does the gravitational force change if the masses of both objects are doubled while the distance between them remains the same? It remains the same It doubles It quadruples It halves None 13. Calculate the orbital period of a satellite orbiting at a distance of 7000 km from the center of the Earth. $ \displaystyle {(\text{Use }g=9.8m/{{s}^{2}})}$ Orbital period: 5000 s Orbital period: 6000 s Orbital period: 7000 s Orbital period: 8000 s None 14. Where is the centre of gravity of a uniform, symmetrical object located? At its base At its top At its geometric center At its edge None 15. A 3 kg object is lifted to a height of 4 meters. Calculate its gravitational potential energy. $ \displaystyle {(\text{Use }g=9.8m/{{s}^{2}})}$ Potential energy: 58.8 J Potential energy: 78.4 J Potential energy: 98.0 J Potential energy: 117.6 J None 16. Calculate the gravitational force between two 10 kg masses separated by a distance of 5 meters$ \displaystyle (UseG=6.67\times {{10}^{{-11}}}N{{m}^{2}}/k{{g}^{2}})$$ \displaystyle (UseG=6.67\times {{10}^{{-11}}}N{{m}^{2}}/k{{g}^{2}})$ $ \displaystyle \mathbf{Gravitational}\text{ }\mathbf{force}:2.67\times {{10}^{{-11}}}N$ $ \displaystyle \mathbf{Gravitational}\text{ }\mathbf{force}:2.67\times {{10}^{{-10}}}N$ $ \displaystyle \mathbf{Gravitational}\text{ }\mathbf{force}:1.33\times {{10}^{{-11}}}N$ $ \displaystyle \mathbf{Gravitational}\text{ }\mathbf{force}:1.33\times {{10}^{{-9}}}N$ None 17. If a person has a mass of 60 kg, what would be their weight on Earth? $ \displaystyle {(\text{Use }g=9.8m/{{s}^{2}})}$ Weight: 58.8 N Weight: 588 N Weight: 60 N Weight: 600 N None 18. What is the gravitational field strength at a height where the gravitational acceleration is $ \displaystyle 6.7m/{{s}^{2}}$ ? Field strength: 6.5 N/kg Field strength: 7.5 N/kg Field strength: 8.5 N/kg Field strength: 9.5 N/kg None 19. How far will an object fall in 6 seconds if it is dropped from rest? $ \displaystyle {(\text{Use }g=9.8m/{{s}^{2}})}$ Distance: 88.2 meters Distance: 176.4 meters Distance: 264.6 meters Distance: 352.8 meters None 20. If a person has a mass of 75 kg on Earth, what would be their mass on Mars? Mass: 25 kg Mass: 50 kg Mass: 75 kg Mass: 100 kg None 21. If the height of an object is halved, how does its gravitational potential energy change? It remains the same It doubles It halves It quadruples None 22. Why do astronauts experience weightlessness in a space station orbiting the Earth? Because there is no gravity in space Because the space station is in free fall Because they are far from Earth Because the space station has no mass None 23. If the distance between two objects is reduced by half, how does the gravitational force between them change? It becomes one-fourth It becomes one-half It becomes twice It becomes four times None 24. Which of the following forces is responsible for the orbital motion of planets around the Sun? Centripetal force Centrifugal force Frictional force Magnetic force None 25. What is the value of acceleration due to gravity at the surface of the Moon? $ \displaystyle 1.6m/{{s}^{2}}$ $ \displaystyle 3.7m/{{s}^{2}}$ $ \displaystyle 5.5m/{{s}^{2}}$ $ \displaystyle 9.8m/{{s}^{2}}$ None 1 out of 25 Time's up