# Example 8.3 - Chapter 8 Class 9 - Motion

Last updated at June 11, 2019 by Teachoo

Last updated at June 11, 2019 by Teachoo

Transcript

Example 8.3 Usha swims in a 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. Given Length of the pool = 90 m Time taken = 1 minute = 60 seconds Usha travels from A to B, then back from B to A Distance travelled = AB + BA = 90 + 90 = 180 m Since she comes back to initial position, Displacement = 0 Average Speed Distance = AB + BA = 90 + 90 = 180 m Average speed = (๐๐๐ก๐๐ ๐๐๐ ๐ก๐๐๐๐)/(๐๐๐ก๐๐ ๐ก๐๐๐) = 180/60 = 3 m/s Average Velocity Since she comes back to initial position, Displacement = 0 Average velocity = ๐ท๐๐ ๐๐๐๐๐๐๐๐ก/(๐๐๐๐ ๐ก๐๐๐๐) = 0/60 = 0 m/s

Examples from NCERT Book

Class 9

Chapter 8 Class 9 - Motion

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.