Test: Gravitation- Assertion & Reason Type Questions- 2

# Test: Gravitation- Assertion & Reason Type Questions- 2 - Class 9

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## 14 Questions MCQ Test Physics for Class 9 - Test: Gravitation- Assertion & Reason Type Questions- 2

Test: Gravitation- Assertion & Reason Type Questions- 2 for Class 9 2023 is part of Physics for Class 9 preparation. The Test: Gravitation- Assertion & Reason Type Questions- 2 questions and answers have been prepared according to the Class 9 exam syllabus.The Test: Gravitation- Assertion & Reason Type Questions- 2 MCQs are made for Class 9 2023 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Gravitation- Assertion & Reason Type Questions- 2 below.
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Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 1

### Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:Assertion : Any two objects in the universe attract each other by a force called gravitation force.Reason : The force of gravitation exerted by the earth is called gravity.

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 1
Gravitational acceleration is the acceleration of an object caused by the force of gravity from another object. In the absence of any other forces, any object will accelerate in a gravitational field at the same rate, regardless of the mass of the object. On the surface of the Earth, all objects fall with an acceleration of somewhere between 9.78 and 9.82m/s2 depending on latitude, with a conventional standard value of exactly 9.80665m/s2.

In a place on the earth, the acceleration due to gravity is constant because it is determined by the mass, and radius of the Earth and not the properties of the object.

Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 2

### Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:Assertion : An object floats if it displaces an amount of liquid whose weight is greater than the actual weight of the object.Reason : During floatation an object experiences no net force in the downward direction.

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 2
Net force = real weight - upthrust (weight of the liquid displaced).

The object rises above the liquid surface to an extent that the weight of the liquid displaced by the part of the object. Thus, an object will float when upward thrust is greater than its actual weight. (The density of the object must be less than the density of the liquid).

Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 3

### Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:Assertion : Universal gravitational constant G is a scalar quantity.Reason : The value of G is same through out the universe.

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 3
The value of G is independent of direction and is a constant through out the universe.
Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 4

Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:

Assertion : If we drop a stone and a sheet of paper from a balcony of first floor, then stone will reach the ground first.

Reason : The resistance due to air depends on velocity only.

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 4
The sheet of paper and piece of stone do not reach the ground simultaneously. Infact, stone reaches the ground before the sheet of paper. This is because resistance of air opposes the motion of sheet of paper more than it opposes the motion of stone.
Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 5

Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:

Assertion : When distance between two bodies is doubled and also mass of each body is doubled, then the gravitational force between them remains the same.

Reason : According to Newton’s law of gravitation, product of force is directly proportional to the product mass of bodies and inversely proportional to square of the distance between them.

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 5
According to Newton's law of gravitation, F = (G(m1m2)/r2)

When m1, m2 ​ and r all are doubled,

F’ = G(2m1)(2m2)/(2r)2 = Gm1m2/r2

which is still equal to F. i.e., force remains the same.

Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 6

Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:

Assertion : The density of a liquid depends upon the nature and temperature of the liquid.

Reason : The volume of the liquid depends upon temperature.

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 6
Density = mass/volume

The density of a liquid depends on the kind of liquid and its temperature. Volume increases with increase in temperature and vice-versa. The density decreases with increase in temperature.

Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 7

Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:

Assertion : The value of the acceleration due to gravity g on earth depends upon the average density of the earth.

Reason : It is the radius of the earth which determines the value of the g .

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 7
Since g = (G(M/R2), the acceleration due to gravity depends both on average density and the average radius of the earth.
Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 8

Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:

Assertion : When the orbital radius of a planet is made 4 times, its time period increases by 8 times.

Reason : Greater the height above the earth’s surface, greater is the time period of revolution.

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 8
According to Kepler’s law, T2 ∝ r3 or T ∝ r3/2

When r becomes four times, T is 43/2 (= 23) = 8 times.

Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 9

Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:

Assertion : The value of acceleration due to gravity changes with the height, depth and shape of the earth.

Reason : Acceleration due to gravity is zero at the centre of the earth.

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 9
The value of g changes with height, depth and is zero at the centre of the earth.
Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 10

Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:

Assertion : Weight of a body on earth is equal to the force with which the body is attracted towards the earth.

Reason : Weight of a body is independent of the mass of the body.

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 10
The weight of a body is the force with which the earth attracts it. The weight is equal to the product of mass and acceleration due to gravity.
Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 11

Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:

Assertion : When a body is thrown up, the acceleration due to gravity at the topmost point is zero.

Reason : The acceleration due to gravity is always directed downwards towards the centre of the earth for a freely falling body.

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 11
Acceleration due to gravity at the topmost point in case of a stone thrown upward is not zero.
Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 12

Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:

Assertion : By tying a stone to a wooden plank, an object can be made such that it floats in a river and sinks in the ocean.

Reason : Density of river water is more than the density of sea-water.

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 12
The density of sea-water is greater than the density of river water. Therefore, the buoyant force will be larger in sea-water which keeps the body float.
Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 13

Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:

Assertion : An object floats on the surface of a liquid in a beaker. The whole system is allowed to fall freely under gravity. The upthrust on the object due to the liquid is equal to the weight of the liquid displaced.

Reason : Archimedes’ principle states that the upthrust on an object due to a fluid is equal to the weight of the fluid displaced.

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 13
• When the beaker is permitted to fall naturally, the body's visible weight becomes zero, implying that the body exerts no impact on the water. As a result, no water is displaced because of the body's weight. Therefore, the buoyant force, or upthrust, would be zero.

• Archimedes' principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether fully or partially, is equal to the weight of the fluid that the body displaces. Archimedes' principle is a law of physics fundamental to fluid mechanics.

Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 14

Direction : In each of the following questions, a statement of Assertion is given and a corresponding statement of Reason is given just below it. Of the statements, given below, mark the correct answer as:

Assertion : A sheet of paper falls slower, than one that is crumpled in to a ball?

Reason : Sheet of paper has lesser weight than that is crumpled into a ball.

Detailed Solution for Test: Gravitation- Assertion & Reason Type Questions- 2 - Question 14
By crumpling the paper into a ball, the volume of the object decreases but the mass remains the same. Hence its density increases.

As air applies some resistance on falling sheet of paper as well as crumpled ball but the resistance to the motion of crumpled ball through the air decreases that makes it to fall faster than the sheet of paper.

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