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

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Suppose an aeroplane travels distance of 1600 kilometers in 2 Hours
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What is speed of Plane
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Distance = 1600 km

Time = 2 hours

Speed = Distance/Time

= 1600/2

= 800 Km/Hour

## Example 2

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Suppose an athlete runs 200 meter race in 25 seconds
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What is his speed in meter per second?
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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

## Questions

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

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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?
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