- Books Name
- Science Made Easy Science Book

- Publication
- Science Made Easy

- Course
- CBSE Class 9

- Subject
- Science

**Distance and Displacement **

**Distance -**The actual path or length travelled by the object travelled by the object is called the distance.

It is a scalar quantity.

It is always positive.

It can never be zero or negative.

**Displacement – **It is the shortest path between initial and final point.

It is a vector quantity.

It can be positive or negative.

It can be zero.

**Difference bw distance and displacement**

**Example 1: **A body travels in a semicircular path of radius 10 m starting its motion from point ‘A’ to point ‘B’. Calculate the distance and displacement.

**Example 2:** A body travels 4 km towards North then he turn to his right and travels another 4 km before coming to rest. Calculate (i) total distance travelled, (ii) total displacement.

**Velocity - **It is defined as the displacement of the body per unit time.

**Velocity = **displacement travelled / time taken

**SI unit = **m/s (meter/second)

**Average Velocity - **The average velocity of a body is the total displacement travelled by the total time taken to cover this distance.

**Average velocity= **Total Displacement/Total Time taken

**Avg. Velocity (vavg) =** (Initial velocity + Final velocity)/2 = (u+v)/2

**where, u =** initial velocity**, v =** final velocity

**Example 1: **During first half of a journey by a body it travel with a speed of 40 km/hr and in the next half it travels with a speed of 20 km/hr. Calculate the average speed of the whole journey.

**Example 2 : **If Ananya was able to travel 6 km in North in 2 hour in his car. What was her velocity?

**Example 3:** A car travels 20 km in first hour, 40 km in second hour and 30 km in third hour. Calculate the average speed of the train.