Free download NCERT Solutions for Class 9 Science Chapter 8 Motion in PDF form. **NCERT Solutions** for Class 9 all Subjects based on **Latest CBSE Syllabus** are available to free download. Download the solutions for all Chapters of **Class 9 Science**.

## NCERT Solutions for Class 9 Science Chapter 8

### Class 9 Science – Physics -Motion

#### Important Questions with answers

**Question 1**:

A train travels 100 m long moving on a straight level track passes a pole in 5 s. Find (a) the speed of the train (b) the time it will take to cross a bridge 500m long.**Answer 1**:

(a) 20 m/s

(b) 30 s**Question 2**:

A car travelling at 36 km/h speeds upto 72 km/h in 5 seconds. What is its acceleration? If the same car stops in 20 seconds, what is the retardation?**Answer 2**:

2 m/s² ; -1 m/s²**Question 3**:

Usha swims in 90 m long pool. She covers 180 m in one minute by swimming from one end to the other and back along the same straight path. Find the average speed and average velocity of usha.**Answer 3**:

3 ms^-1 ; zero**Question 4**:

Ahmed is moving in his car with a velocity of 45 km/h. How much distance will he cover (a) in one minute and (b) in one second?**Answer 4**:

750 m ; 12.5 m**Question 5**:

A train starting from rest attains a velocity of 72 km h^-1 in 5 minutes. Assuming that the acceleration is uniform, find (i) the acceleration and (ii) the distance travelled by the train for attaining this velocity.**Answer 5**:

1/15 m/s² ; 3 km**Question 6**:

A body starts to slide over a horizontal surface with an initial velocity of 0.5 m/s. Due to friction, its velocity decreases at the rate of 0.05 m/s². How much time will it takes for the body to stop?**Answer 6**:

10 seconds**Question 7**:

A car accelerates uniformly from 18 km/h to 36 km h/ in 5 second. Calculate (i) the acceleration and (ii) the distance covered by the car in that time.**Answer 7**:

1 m/s² ; 37∙5 m**Question 8**:

What does the odometer of an automobile measure?**Answer 8**:

The odometer of an automobile measures the distance travelled by the vehicle.**Question 9**:

What is the nature of the distance-time graph for uniform and non-uniform motion of an object?**Answer 9**:

When the motion is uniform, the distance-time graph is a straight line with some slope.

When the motion is non-uniform, the distance time graph is not a straight line. It can be any curve.**Question 10**:

What is locomotion?**Answer 10**:

Locomotion is the ability of an animal to move its whole body from place to place without any external forces.**Question 11**:

What type of motion of tips of second’s hand of a watch? Is it uniform or accelerated?**Answer 11**:

The motion of the tip of second’s hand of a watch is not a uniform motion. It is accelerated motion due to change in the direction of motion.**Question 12**:

Define speed and velocity. What are their SI units?**Answer 12**:

Speed: Speed of a body is defined as the distance travelled by the body in unit time.

Velocity: Velocity of a body is the distance travelled by the body in unit time in a given direction.

The SI unit is meter/second.