Kerala Syllabus Class 9 Physics - Chapter 4 Gravitation - Questions and Answers
Questions and Answers for Class 9 Physics ഗുരുത്വാകർഷണം | Text Books Solution Physics (English Medium) Physics: Chapter 04 Gravitation - SAMAGRA Questions Bank
ഒമ്പതാം ക്ലാസ്സ് ഫിസിക്സിലെ Gravitation എന്ന പാഠം ആസ്പദമാക്കി samagra തയ്യാറാക്കിയ ചോദ്യോത്തരങ്ങള്.
Class 9 Physics Gravitation - SAMAGRA Question Bank
∎Physics (English Medium Notes)
1. The spring stretches when a 100-gram block is suspended from a spring balance held by a finger. Explain the reason for this phenomenon.
(gravity, elasticity, buoyant force, surface tension)
Answer: gravity
2. The stretching of the spring of a spring balance increases with an increase in the .............. of the block hung on it
(size, mass, length, weight)
Answer: mass
3. The force of attraction between two objects is inversely proportional to the .............. between them.
(mass, weight, distance, the square of distance)
Answer: the square of distance
4. The value of G is 6.67 x 10⁻¹¹ ..............
(N²m²/kg², N²m²kg², Nm²/kg², Nm²/kg)
Answer: Nm²/kg²
5. If x is the force of attraction with which an object with a mass of 40 kg is attracted by an object with a mass of 80 kg, then the of attraction with which an object with a mass of 40 kg attracts a body of mass 80 kg is ..............
Answert: x
6. The acceleration due to gravity g = ..............
(G/MR², GR²/M, MR²/G, GM/R²)
Answer: GM/R²
7. The value of 'g' is the maximum .............. of the Earth.
(at the equator, at the centre, in space, in the polar region)
Answer: In the polar region
8. What is the value of g at the centre of the Earth?
Answer: zero
9. The force with which an object is attracted by the Earth is its ..............
(Mass, volume, density, weight)
Answer: weight
10. The value of g on the Moon is .............. m/s²
(16.2, 9.8, 1/62, 1.62)
Answer: 1.62
11. The reason why objects moving in a circular path have acceleration even if they have a uniform speed is because ..............
(the speed decreases, the direction changes, there is a pulling force towards the centre, they go along a tangent)
Answer: the direction changes
12. The direction of the acceleration of an object moving in a circular path is ..............
(outwards, along the tangent, towards the centre, no acceleration)
Answer: towards the centre
13. The weight experienced by a freely falling object is ..............
Answer: zero
14. From where do artificial satellites get the required centripetal force?
( Moon, Earth, Rocket, Sun )
Answer: Earth
15. Mass, the curvature of the curve, and the .............. are the factors that influence the tendency of a vehicle running through the curves to turn around.
Answer: speed
16. The force of attraction between an object and the earth depends on what factors?
Answer: the mass of the object and the distance from the centre of the earth
17. What is the reason why the weight of the object at the centre of the earth is zero?
Answer: Since the value of g at the centre of the earth is zero
18. Gravity.
Answer: Earth attracts all objects. The direction of this force is towards the centre of the Earth. This force of attraction is the force of gravity.
19. State the law of universal gravitation.
Answer: All objects in the universe attract each other. The force of attraction between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
20. Where did the object of mass 100 kg experience a greater force of attraction?
(on the surface /at a height of 1,00,000 m / at a height of 10,00,000 m)
Answer: on the surface
21. As the distance from the Earth to the object increases, the force of attraction exerted by the Earth (increases/decreases)
Answer: decreases
22. What will be the force of attraction experienced when two objects of 40 kg and 50 kg mass are 3 m apart when they are on the moon?
Answer:
23. The Earth attracts objects with greater force when they have a higher mass. However, a heavy object and a light object dropped from the same height at the same time will fall to the ground at the same time. Why?
Answer: Because they are equally accelerated by the attraction from the earth or g is independent of the mass of the object.
24. If an object is weighed on a spring balance at the Earth's poles and then transported to the equator and weighed again on the same balance, would there be a change in its measured weight? Justify your answer.
Answer: There will be a change. Since the value of g is not the same in equatorial and polar regions
26. Why is the value of g different on Earth and on the Moon?
Answer: g=GM/R², because of the difference in the mass(M) and radius(R) of the earth and the moon
27. If a mango and a leaf fall from the same height at the same time then they will not reach the ground at the same time. What could be the reason?
Answer: Because the leaf experiences more resistance from air
28. What does it mean to be in freefall? What causes you to feel weightless in a freefall?
Answer: If an object is allowed to fall freely from a height, it will fall to the ground only under the gravitational force of the Earth. Such a motion is called free fall.
Since the entire weight of the object is used for gravitational acceleration.
29. What is the reason for the acceleration of the object moving in the circular path even if it has uniform speed?
Answer: As the direction of motion of the object changes.
30. What does it mean by centripetal force? How does the inadequacy of the centripetal force influence the motion of an object?
Answer: Acceleration of an object moving along a circular path is centripetal acceleration. The force required for this acceleration is centripetal force. If the object in circular motion does not receive sufficient centripetal force, the object will be thrown along the tangent.
31. What are the factors that influence the tendency of vehicles to topple over at curves?
Answer: Mass, speed, the curvature of the road
32. What is the direction of the centripetal force? Where do artificial satellites orbiting the Earth get centripetal force from?
Answer: Towards the centre of the earth. From the Earth
33. Calculate the weight of an object with a mass of 20 kg on Earth, the moon and Jupiter in newton(N). (gₑ – 9.8 m/s², gₘ– 1.62 m/s², gj - 24.5 m/s²)
Answer:
• The weight on earth (mg) is 196 N
• Weight on the Moon is 32.4 N
• Weight on Jupiter is 490 N
34. State the law of universal gravitation. How can this be expressed mathematically? What is the value of the universal gravitational constant?
Answer:
• All objects in the universe attract each other. The force of attraction between two objects is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
• F=Gm1m2r2
• The value of the universal gravitational constant, often denoted as G, is approximately 6.674 × 10⁻¹¹ N·m²/kg².
• The value of the universal gravitational constant, often denoted as G, is approximately 6.674 × 10⁻¹¹ N·m²/kg².
35. a) When the distance between two objects is halved, the force of attraction ..............
(is halved, is doubled, is four times, square times)
b) Two persons standing nearby do not come and touch each other automatically due to the attractive force between them. Why?
Answer:
a) is four times
b) The force of attraction between the person and the earth is very large.
36. Explain the feather and coin experiment.
A coin and a feather are placed in a long transparent tube. When it is held vertically and then suddenly turned upside down, it is seen that the feather reaches the bottom shortly after the coin. If the air inside the tube is removed and the experiment is repeated, it can be seen that both the feather and the coin reach the bottom simultaneously.
37. Skylab, an artificial satellite sent for space exploration, had a mass of approximately 90,000 kg. It stopped working when it was about 435 km above the earth's surface. Due to the mutual force between the satellite and the Earth, the Earth should also have fallen into the Skylab. But the Skylab fell to the earth. Why didn't the Earth fall into the Skylab? Explain the reason.
Answer: The mass of the earth and thus the force of attraction is very large compared to the skylab, so the acceleration of the skylab towards the earth is very large.
38. Tabulate the differences between mass and weight.
Answer:
| Mass | Weight |
|---|---|
| • Measured using common balance | • Measured using spring balance |
| • Scalar quantity Remains | • vector quantity |
| • Remains constant everywhere in the universe | • Various depending on the gravitational pull |
| • SI Unit kilogram (kg) | • SI Unit Newton (N) or kilogram weight (kgwt) |
| • The amount of matter in an object | • The force with which an object is attracted by the Earth or a planet. |
39. a) What is the weight on the earth's surface of an object of 50 kg mass?
b) What is the weight of the object at the centre of the earth?
c) What will be the mass of this object on the surface of the moon?
d) How do you measure mass and weight?
Answer:
a) W = mg = 490.5 N
b) zero
c) 50 kg
d) mass - common balance
weight - spring balance
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