# Distance, Time and Speed

*What is speed?*

*What is speed?*

Speed describes how fast an object is moving. In other words, speed tells us the distance an object travels per unit of time.

The various units of speed are:

- cm/s (read as, centimetres per second)
- m/min (read as, metres per minute)
- m/s (read as, metres per second)
- km/h (read as, kilometres per hour)

*Examples*

*Examples*

The ant below crawls from Anthill A to Anthill B in 100 seconds.

The ant crawls 200 cm in 100 seconds.

In 1 s, the ant crawls 2 cm.

The ant's crawling speed is 2 cm/s.

The girl below walks from home to school in 12 minutes.

The girl walks 720 m in 12 minutes.

The girl walks 60 m in 1 min.

The girl's walking speed is 60 m/min.

The soccer ball travels from Goalpost P to Goalpost S in 5 seconds.

The ball travels 90 m in 5 s.

In 1 s, the ball travels 18 m.

The ball travels at an speed of 18 m/s.

The bus below travels from Town X to Town Y in 1 hour.

In 1 hour, the bus travels 55 km.

The bus is travelling at a speed of 55 km/h.

At this speed, how long will it take to reach Town Z from Town Y?

The bus will take 2 hours to reach Town Z from Town Y.

55 km 1 h 110 km 2 h

At this speed, how far will the bus be 1

2h after it leaves Town Z?

1 h 55 km 1

2h 55 km

2= 27.5 km

The bus will be 27.5 km away 1

2h after it leaves Town Z.

Speed | = | Distance travelled Time taken |

Distance travelled | = | Speed × Time taken |

Time taken | = | Distance travelled Speed |

*Word Problem 1*

*Word Problem 1*

A bird flies in search of food from her nest in a tree to a stream 1800 metres away in 3 minutes. What is the speed at which she flies?

Distance travelled = 1800 m Time taken = 3 min Speed = 1800 m

3 min= 600 m/min

The bird flies at a speed of 600 m/min.

*Word Problem 2*

*Word Problem 2*

A lorry is going at a speed of 40 km/h. At this speed, how far can it go in

1

2h?

Speed = 40 km/h Time taken = 1

2h Distance travelled = 40 km/h × 1

2h = 20 km

It can go 20 km in 1

2h.

*Word Problem 3*

*Word Problem 3*

A train is running at a speed of 180 km/h. At this speed, how long will the train take to travel the 270-km long distance between Station A and Station B?

Speed = 180 km/h Distance travelled = 270 km Time taken = 270 km

180 km/h= 3

2h = 1 1

2h

The train will take 1 1

2h to travel the distance between Station A and Station B.