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# Test: Gravitation- Assertion & Reason Type Questions- 1

## 10 Questions MCQ Test Science Class 9 | Test: Gravitation- Assertion & Reason Type Questions- 1

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Attempt Test: Gravitation- Assertion & Reason Type Questions- 1 | 10 questions in 20 minutes | Mock test for Class 9 preparation | Free important questions MCQ to study Science Class 9 for Class 9 Exam | Download free PDF with solutions
QUESTION: 1

### Direction : In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:Assertion : On moon, man feels lighter than earth.Reason : Due to more gravitational force exerted by moon on man.

Solution: On moon, man feels lighter than earth. It is due to less gravitational force exerted by moon on man.
QUESTION: 2

### Direction : In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:Assertion : Mass of an object is always zero.Reason : Mass of an object is the measure of its inertia and the substance contained by the body.

Solution: Mass of an object can never be zero because mass of an object is the measure of its inertia and the substance contained by the body.
QUESTION: 3

### Direction : In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:Assertion : An object thrown vertically upward with certain velocity v, reaches maximum height and fall back with same velocity.Reason : Whenever an object falls towards the earth, gravitational force of the earth causes acceleration.

Solution: When an object is thrown vertically upward with certain velocity, it will fall back freely. There will be a change in the magnitude of velocity due gravitational force of the earth.
QUESTION: 4

Direction : In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:

Assertion : If the distance between two bodies of mass m1 and m2 is increased by a factor of 5, the gravitational force is reduced by 1/25.

Reason: The gravitational force is inversely proportional to the square of the distance between two bodies.

Solution: Gravitational force is given by the formula F = GMm/R2. Gravitational force is inversely proportional to the square of the distance between two bodies.
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 : At the centre of earth, a body has a centre of mass but no centre of gravity.

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

Solution: At the centre of the earth value of g is zero, weight of the body is also zero but its mass remains the same. The centre of mass of the body thus remains unchanged.
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 : A man is sitting in a boat which floats on a pond. If the man drinks some water from the pond, the level of water in the pond will decrease.

Reason : The weight of the liquid displaced by the body is greater than the weight of the body.

Solution: Water level in the pond remains unchanged. When the man drinks water from the pond, a larger volume of water is displaced by the boat and hence or original water level is maintained.
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 : A block of ice with a lead shot embedded in it floats on water contained in a vessels. The temperature of the system is kept at 0cC as the ice melts. When ice has melted completely, water level in the vessel rises.

Reason : The melted ice will raise the water level.

Solution: The water level in the vessel remains unchanged. The volume or melted ice and lead shot, is equal to the volume of the water displaced when the ice block with lead shot is initially placed in water.
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 : During a journey from the earth to the moon and back, maximum fuel is spent to overcome the earth’s gravity at take off.

Reason : Earth’s mass is much greater than that of the moon.

Solution: Since the earth’s mass is much more than that of the moon, the gravitational force exerted by the earth on the spaceship is much greater than that exerted by the moon. The work done is much greater.
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 : Kepler’s second law of planetary motion is also known as Kepler’s law of areas.

Reason : The line joining the planet and the sun sweeps equal areas in equal intervals of time.

Solution: Kepler's Second Law: An imaginary line joining a planet and the sun sweeps out an equal area of space in equal amounts of time. The animation below depicts the elliptical orbit of a planet about the sun.
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 : It is the gravitational force exerted by the sun and the moon on the sea water that causes to the formation of tides in the sea.

Reason : Gravitational force of attraction is a strong force.

Solution: Gravitational force of attraction is the reason behind the formation of tides. It is a weak force.
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