Distance is used to measure how far two objects are from each other.

**Definition of distance**

The distance between two points is the length of the straight line segment joining them. The distance of a point from a given line, is determined by measuring the length of the perpendicular line drawn from the point to the line. This perpendicular line is the shortest line segment that can be drawn from the point to the line.

Now that we know the definition of Distance, let us look at the definition of speed. Speed is defined as the distance travelled over time. Speed is commonly measured in meters per second or kilometers per hour.

**Formula**

Distance = Speed x Time

Time = Distance/Speed

Speed= Distance/Time

Remember, if the distance is provided in kms and time in hours then the units of speed will be kms/ hour.

Similarly if distance is provided in meters and speed is provided in meters/ second then the unit of time will be seconds.

You can convert between meters and kilometers using the formula 1 kilometer = 1000 meters.

**Practice questions**

Question: John cycles at an average speed of 6 kms per hour. What is the distance travelled by John if he cycles for 4 hours without taking a break?

( Answer: Distance = Speed * Time

= 6 * 4

= 24 kms

)

Question: An athlete covers 360 mts in 30 seconds on a race track - what is his speed?

( Answer: Speed = Distance / Time

= 360 / 30

= 12 mts per second

)

Question: Lea runs for 1 hour daily at a speed of 5 kms / hour. How much distance does she cover in a week?

( Answer: Distance = Speed * Time

= 5 * 1

= 5 hours daily

Distance covered in a week = 5 * 7 = 35 kms.

)

Question: Josh drives for 200 kms at an average speed of 50 kms / hour. For how long was he travelling?

( Answer: Time = Distance / Speed

= 200 / 50

= 4 hours

)

Question: Adi leaves Mumbai at 8:00 am and reaches Pune by 10:00 am. If the distance between the two is 80 kms, find Adi’s average speed.

( Answer: Time taken by Adi to travel from Mumbai to Pune = 2 hours

Distance between Mumbai and Pune = 80 kms

Speed = Distance / Time

= 80 / 2

= 40 kms / hour

)

**Related terms**

The velocity of an object is defined as its speed in a particular direction. Thus two cars travelling at the same speed but in different directions will have different velocities.

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