Class 9 Science Chapter 9 Gravitation – One Liner Questions and Answers | Notes Prepare for CBSE Class 9 Science Chapter 9 Gravitation with important one-liner questions and answers. Quick revision notes covering universal law of gravitation, free fall, buoyancy, Archimedes’ principle, and more!
Q1. Who discovered the universal law of gravitation?
Ans. Isaac Newton discovered the universal law of gravitation.
Q2. What is the force that attracts objects towards the center of the Earth?
Ans. Gravitational force attracts objects towards the center of the Earth.
Q3. What is the shape of the path traced by the stone when whirled in a circle and released?
Ans. It moves along a tangent to the circle.
Q4. What is the force acting towards the center in circular motion called?
Ans. It is called centripetal force.
Q5. State the Universal Law of Gravitation.
Ans. Every object attracts every other object with a force proportional to the product of their masses and inversely proportional to the square of the distance between them.
Q6. What is the value of the universal gravitational constant (G)?
Ans. G = 6.673 × 10⁻¹¹ N m² kg⁻².
Q7. Who determined the value of G?
Ans. Henry Cavendish determined the value of G.
Q8. What is free fall?
Ans. When an object falls under the influence of gravitational force alone, it is called free fall.
Q9. What is the acceleration due to gravity symbolized as?
Ans. It is symbolized as “g”.
Q10. What is the standard value of acceleration due to gravity on Earth?
Ans. 9.8 m/s².
Q11. What is the formula for gravitational force (F) between two masses (M and m) separated by distance d?
Ans. F = G × (M × m) / d².
Q12. Does the mass of an object change with location?
Ans. No, mass remains constant everywhere.
Q13. What is weight?
Ans. Weight is the force with which an object is attracted towards the center of the Earth.
Q14. What is the formula for weight (W)?
Ans. W = m × g.
Q15. What is the SI unit of weight?
Ans. Newton (N).
Q16. How is weight on the Moon related to weight on Earth?
Ans. Weight on the Moon is 1/6th of the weight on Earth.
Q17. What is thrust?
Ans. Thrust is the force acting perpendicular to the surface.
Q18. Define pressure.
Ans. Pressure is thrust per unit area.
Q19. What is the SI unit of pressure?
Ans. Pascal (Pa).
Q20. What is buoyancy?
Ans. Buoyancy is the upward force exerted by a fluid on an object immersed in it.
Q21. What determines whether an object floats or sinks in a fluid?
Ans. The density of the object compared to the fluid.
Q22. What happens when the density of an object is less than that of the liquid?
Ans. The object floats.
Q23. What happens when the density of an object is more than that of the liquid?
Ans. The object sinks.
Q24. What is Archimedes’ Principle?
Ans. When a body is immersed in a fluid, it experiences an upward buoyant force equal to the weight of the fluid displaced.
Q25. What is the application of Archimedes’ Principle?
Ans. It is used in designing ships, submarines, lactometers, and hydrometers.
Q26. Why is it difficult to hold a school bag with thin straps?
Ans. Because it exerts more pressure on the shoulder due to smaller area.
Q27. Why does a block of plastic released underwater rise up?
Ans. Because the buoyant force is greater than the weight of the plastic.
Q28. In which direction does the buoyant force act on an object submerged in a fluid?
Ans. It acts in the upward direction.
Q29. Why does a ship made of iron float while an iron nail sinks?
Ans. Because the ship’s average density is less than water, but the nail’s density is more.
Q30. What is the formula to calculate pressure?
Ans. Pressure = Thrust / Area.
Prepare for CBSE Class 9 Science Chapter 9 Gravitation with important one-liner questions and answers. Quick revision notes covering universal law of gravitation, free fall, buoyancy, Archimedes’ principle, and more!