Test: Motion- Assertion & Reason Type Questions

# Test: Motion- Assertion & Reason Type Questions - Class 9

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## 15 Questions MCQ Test Physics for Class 9 - Test: Motion- Assertion & Reason Type Questions

Test: Motion- Assertion & Reason Type Questions for Class 9 2023 is part of Physics for Class 9 preparation. The Test: Motion- Assertion & Reason Type Questions questions and answers have been prepared according to the Class 9 exam syllabus.The Test: Motion- Assertion & Reason Type Questions MCQs are made for Class 9 2023 Exam. Find important definitions, questions, notes, meanings, examples, exercises, MCQs and online tests for Test: Motion- Assertion & Reason Type Questions below.
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Test: Motion- Assertion & Reason Type Questions - 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 : A stone tied with a piece of thread describing a circular path with constant velocity on being released moves in a straight line.Reason : Along the circular path direction of motion remains the same at every point.

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 1
In a circular path direction of motion changes at every point. The direction of motion at any point is the tangent to that point in circular path.
Test: Motion- Assertion & Reason Type Questions - 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 : When the displacement of a body is directly proportional to the square of the time. Then the body is moving with uniform acceleration.Reason : The slope of velocity-time graph with time axis gives acceleration.

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 2
When displacement of body is given by

So differentiating t^2 with respect to dt will result 'v' as 2t.

Now again differentiating v with respect to dt we get 'a' as 2.

Hence the body will have zero acceleration as the value of 'a' is constant

Test: Motion- Assertion & Reason Type Questions - 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 can have constant speed but variable velocity. Reason: Speed is a scalar but velocity is a vector quantity.

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 3

Since velocity is a vector quantity, hence as its direction changes keeping magnitude constant, velocity is said to be changed. But for constant speed in equal time interval distance travelled should be equal.

Test: Motion- Assertion & Reason Type Questions - 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 : The displacement of an object can be either positive, negative or zero.

Reason : Displacement has both the magnitude and direction.

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 4

Correct answer is option A. Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).

Test: Motion- Assertion & Reason Type Questions - Question 5

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

Assertion : A boy riding on bicycle in a crowded street exhibit non uniform motion.

Reason : The boy covers equal distance in equal interval of time.

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 5
Boy riding on the bicycle exhibit non uniform motion. He covers unequal distance at different interval of time.
Test: Motion- Assertion & Reason Type Questions - Question 6

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 a particle is moving with constant velocity, then average velocity for any time interval is equal to instantaneous velocity.

Reason : If average velocity of a particle moving on a straight line is zero for a given time interval, then instantaneous velocity at some instant within this interval may be zero.

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 6
Average velocity Vav = Total displacement/Total elapsed time = Vt/t = V

= Instantaneous velocity

Hence, assertion is correct. If a particle is in a round trip on a straight line, then average velocity is zero but at the instant at which the particle reverses its direction of motion, velocity is zero.

So, reason is correct. But reason is not the correct explanation of assertion.

Test: Motion- Assertion & Reason Type Questions - Question 7

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

Assertion : Displacement for a course of motion may be zero but the corresponding distance covered is not zero.

Reason : Displacement and distance covered may not always equal.

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 7
Distance covered by an object is the total path length while displacement is the shortest distance measured from initial position to the final position of an object.
Test: Motion- Assertion & Reason Type Questions - Question 8

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

Assertion : Motion with uniform velocity is always along a straight line path.

Reason : In uniform velocity a motion, speed is the magnitude of the velocity and is equal to the instantaneous velocity

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 8
The assertion is true and the reason is not the correct explanation of the assertion. Uniform velocity means that speed and direction remain unchanged.
Test: Motion- Assertion & Reason Type Questions - Question 9

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

Assertion : A tiger can accelerate from rest at the rate of 4 m/s2.

Reason : The velocity attained by it in 10 s is 40 m/s.

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 9
Initial velocity (u) = 0, acceleration (a) = 4 m/s2

v = u + at

v = 0 + 4 × 10 = 40 m/s.

Test: Motion- Assertion & Reason Type Questions - Question 10

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 may have acceleration even if it is moving with uniform velocity.

Reason : An object may be moving with uniform velocity but it may be changing its direction of motion.

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 10
The uniform motion only means that the object is moving at a constant speed but its direction of motion may be changing at in the case of uniform circular motion. Hence, acceleration is produced in uniform motion due to changes in velocity.
Test: Motion- Assertion & Reason Type Questions - Question 11

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

Assertion : Motion of satellites around their planets is considered an accelerated motion.

Reason : During their motion, the speed remains constant, while the direction of motion changes continuously.

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 11
Satellites revolve around their planets in almost circular orbits with constant speed. Thus, during their motion, the speed remains constant, while the direction of motion changes continuously. As a result, there is a change in their velocity. Therefore, the motion of satellites around their planets is considered as accelerated motion.
Test: Motion- Assertion & Reason Type Questions - Question 12

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

Assertion : The speedometer of a car measures the instantaneous speed of the car.

Reason : Average speed is equal to the total distance covered by an object divided by the total time taken.

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 12
The speedometer of a car measures the instantaneous speed of the car.
Test: Motion- Assertion & Reason Type Questions - Question 13

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

Assertion : Weight of an object is the force with which a body is attracted towards the earth.

Reason : Its direction is vertically upward.

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 13
Weight of an object is the force with which a body is attracted towards the earth. Its direction is vertically downwards.
Test: Motion- Assertion & Reason Type Questions - Question 14

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

Assertion : Velocity versus time graph of a particle in uniform motion along a straight path is a line parallel to the time axis.

Reason : In uniform motion the velocity of a particle increases as the square of the time elapsed

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 14
When a particle is in uniform motion, the magnitude of its velocity at each instant such as t = 0, t = 1s, t = 2s ..... etc. is always constant. Hence the velocity versus time graph for a particle in uniform motion along a linear path is a straight line parallel to the time axis.
Test: Motion- Assertion & Reason Type Questions - Question 15

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

Assertion : Displacement of an object may be zero even if the distance covered by it is not zero.

Reason : Displacement is the shortest distance between the initial and final position.

Detailed Solution for Test: Motion- Assertion & Reason Type Questions - Question 15
When the final position of an object coincides with its initial position, displacement is zero, but the distance travelled is not zero.

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## Physics for Class 9

16 videos|69 docs|56 tests