Suppose a person travels distance of 6 kilometers in 2 hours

What is his speed

His Speed is 3 Kilometers per hour

 

What is Speed

It is distance travelled per unit of time

 

How to Calculate Speed

Speed = Distance/Time

 

How is it measured

It is normally measured in kilometer per hour

Shorter Distances are also measured in meter per seconds

 

Example 1

Suppose an aeroplane travels distance of 1600 kilometers in 2 Hours

What is speed of Plane

Distance = 1600 km

     Time = 2 hours

 

Speed = Distance/Time

 = 1600/2

 = 800 Km/Hour

 

Example 2

Suppose an athlete runs 200 meter race in 25 seconds

What is his speed in meter per second?

 

Distance = 200 m

Time = 25 Seconds

Speed = Distance/Time

Speed = 200 /25 = 8 meter per second

Note

1 Km = 1000 meters

I Meter = 100 centimeters

 

I hour = 60 Minutes

1 Minutes = 60 Seconds

Now, lets find speed in different units

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Questions

Q 3 Page 102 - What does the odometer of an automobile measure? 

View Answer

 

Q 5 Page 102 - A driver of a car travelling at 52 km h–1 applies the brakes and accelerates uniformly in the opposite direction. The car stops in 5 s. Another driver going at 3 km h–1 in another car applies his brakes slowly and stops in 10 s. On the same graph paper, plot the speed versus time graphs for the two cars. Which of the two cars travelled farther after the brakes were applied?

View Answer

 

  1. Class 9
  2. Chapter 8 Class 9 - Motion

Transcript

Example 3 Suppose a bus travels 180 km in 3 hours Calculate speed of bus in Kilometer/hour meter per minute meter per seconds centimeter per seconds Distance = 180 km Time = 3 hours Speed = ๐ท๐‘–๐‘ ๐‘ก๐‘Ž๐‘›๐‘๐‘’/๐‘‡๐‘–๐‘š๐‘’ = (180 ๐‘˜๐‘š)/(3 โ„Ž๐‘œ๐‘ข๐‘Ÿ๐‘ ) = 60 km/hour Calculating Speed in Meter per Minute Speed = 60 km/hour = 60 ๐‘˜๐‘š/โ„Ž๐‘œ๐‘ข๐‘Ÿ = 60 ร— (1000 ๐‘š)/(60 ๐‘š๐‘–๐‘›๐‘ข๐‘ก๐‘’๐‘ ) = 1000 m/minutes As 1 km = 1000 m and 1 hour = 60 minutes Calculating Speed in Meter per seconds Speed = 60 km/hour = 60 ๐‘˜๐‘š/โ„Ž๐‘œ๐‘ข๐‘Ÿ = 60 ร— (1000 ๐‘š)/(3600 ๐‘ ๐‘’๐‘๐‘œ๐‘›๐‘‘) = 1000/60 m/s = 100/6 m/s = 16.66 m/s As 1 km = 1000 m and 1 hour = 60 minutes = 60 ร— 60 seconds = 3600 seconds Calculating Speed in Centimeter per seconds Speed = 60 km/hour = 60 ๐‘˜๐‘š/โ„Ž๐‘œ๐‘ข๐‘Ÿ = 60 ร— (100000 ๐‘š)/(3600 ๐‘ ๐‘’๐‘๐‘œ๐‘›๐‘‘) = 100000/60 m/s = 10000/6 m/s = 1666.66 m/s As 1 km = 1000 m = 1000 ร— 100 cm = 100000 cm and 1 hour = 60 minutes = 60 ร— 60 seconds = 3600 seconds

About the Author

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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.