Average speed Average velocity ≥ 1 . Interpret.

We know that, Distance > | Displacement | - - ( 1 ) , where | | gives the magnitude of a vector. Since Average speed = Distance time and Average velocity = Displacement time , from equation ( 1 ) , we can derive that, Average Speed ≥ Average velocity Or Average Speed Average velocity ≥ 1 Therefore, the average speed is greater than or equal to the magnitude of average velocity.

The data regarding the motion of two different objects A and B are given in the table. Time Distance travelled by A (in m ) Distance travelled by B (in m ) 9 : 30 AM 5 2 9 : 35 AM 10 10 9 : 40 AM 15 19 9 : 45 AM 20 25 9 : 50 AM 25 25 Examine them carefully and state whether the motion of the objects is uniform or non-uniform.

After every 5 s , the distance covered by A is increasing by 5 m . Therefore, the speed of it is constant with time. In case of B , the change in the distance travelled is different for each interval. Therefore, A is in uniform motion, while B is in non-uniform motion.

E M B I B E

Modern's abc+ Of Science - Physics For Class IX>Chapter 1 - Motion>Summative Assessment>Q 15

EASY

9th CBSE

IMPORTANT

Earn 100

An athlete completes one round of a circular track of diameter $49 m$ in $20 s$ . Calculate the distance covered and displacement at the end of $30 s$ .

Important Questions on Motion

EASY

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 1 - Motion>Summative Assessment>Q 1

Can a body at rest be in motion? Give an example.

EASY

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 1 - Motion>Summative Assessment>Q 2

In case of a moving body, can distance travelled be less than displacement?

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 1 - Motion>Summative Assessment>Q 3

Give three differences between distance and displacement.

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 1 - Motion>Summative Assessment>Q 4

\frac{Average speed}{|Average velocity|} \geq 1

. Interpret.

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 1 - Motion>Summative Assessment>Q 5

Give three differences between speed and velocity.

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 1 - Motion>Summative Assessment>Q 6

The data regarding the motion of two different objects A and B are given in the table.

Time	Distance travelled by A (in $m$ )	Distance travelled by B (in $m$ )
$9 : 30 AM$	$5$	$2$
$9 : 35 AM$	$10$	$10$
$9 : 40 AM$	$15$	$19$
$9 : 45 AM$	$20$	$25$
$9 : 50 AM$	$25$	$25$

Examine them carefully and state whether the motion of the objects is uniform or non-uniform.

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 1 - Motion>Summative Assessment>Q 7

At a time when it is cloudy, there may be frequent thunder and lightning. You hear the sound of thunder after observing the lightning stroke. Can you answer why this happens? (Speed of sound in air $= 346 {ms}^{- 1}$ ).

MEDIUM

9th CBSE

IMPORTANT

Modern's abc+ Of Science - Physics For Class IX>Chapter 1 - Motion>Summative Assessment>Q 8

Give an example of each.

(i) acceleration is in the direction of motion.

(ii) acceleration is against the direction of motion.

(iii) acceleration is uniform.

(iv) acceleration is non-uniform.