Chapter 7: Motion Short Questions | science Class 9 CBSE

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Chapter 7: Motion Short Questions | science Class 9 CBSE | ByteNotes.in

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Question 1

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Q1. Define motion.

Motion is the change in position of an object with respect to time.
It is observed when an object changes its position compared to a reference point.
Examples: moving car, falling apple.

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Question 2

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Q2. What is the SI unit of speed?

The SI unit of speed is metres per second (m/s).
Other units include km/h, cm/s.
Used to measure how fast an object moves.

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Question 3

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Q3. Give two examples of uniform motion.

Car moving at constant speed on a straight road.
Earth revolving around the sun.
Both cover equal distances in equal intervals.

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Question 4

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Q4. What is meant by negative acceleration?

When velocity decreases with time, acceleration is negative.
Also called retardation or deceleration.
Example: applying brakes to a moving vehicle.

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Question 5

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Q5. Write formula for average velocity.

Average velocity = (Initial velocity + Final velocity) / 2.
Used when acceleration is uniform.
Helps calculate displacement.

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Question 6

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Q6. Define displacement.

Shortest distance between initial and final position.
It is a vector quantity and has direction.
Can be zero even when distance is not.

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Question 7

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Q7. What does the slope of a distance-time graph indicate?

Slope of distance-time graph = speed.
Steeper slope indicates higher speed.
Flat slope means object is at rest.

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Question 8

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Q8. What does the area under a velocity-time graph represent?

It gives displacement of the object.
Area under line = velocity × time.
Useful for calculating total distance.

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Question 9

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Q9. Define uniform circular motion.

Motion with constant speed along a circular path.
Direction changes continuously.
It is an accelerated motion.

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Question 10

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Q10. Write the three equations of motion.

v = u + at
s = ut + ½at²
v² = u² + 2as

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Chapter sections

Chapter 7: Motion | Short Questions

Q1. Define motion.

Q2. What is the SI unit of speed?

Q3. Give two examples of uniform motion.

Q4. What is meant by negative acceleration?

Q5. Write formula for average velocity.

Q6. Define displacement.

Q7. What does the slope of a distance-time graph indicate?

Q8. What does the area under a velocity-time graph represent?

Q9. Define uniform circular motion.

Q10. Write the three equations of motion.