# Speed, Distance And Time

SPEED RULES

Distance = Speed × Time

 Speed = Distance Time
 Time = Distance Speed

## Example One - Finding Distance

Michael Schumacher won the Formula 1 championship a record 7 times. If his race car travels at 209.205 kilometres per hour (209.205 km/h), how far can it race in 2 hours?

Answer:

 Distance = Speed × Time = 209.205 × 2 = 418.41 km

## Example Two - Finding Speed

The scramjet (Supersonic Combustion Ramjet), still in experimental stage, is expected to dramatically cut travel time of jet aircraft in the next decade. It can travel 1200 metres in 4 seconds. What is its speed?

Answer:

 Speed = Distance = 1200 m = 300 m/s Time 4 s

## Example Three - Finding Time

The world's fastest man, Usain Bolt, sprinted an amazing 10.44 m/s. In how many seconds (to 2 decimal places) did he run 100 metres?

Answer:

 Time = Distance = 100 = 9.58 s Speed 10.44

## Did You Know That...?

The Ariel Atom V8 car accelerates from 0 to 100 km/h in 2.3 seconds.

## Example Four - Converting KM/H to M/S

The experimental sailing boat, Vestas Sailrocket 2, has 2 hydrofoils, one of which is used to counterbalance the fixed sail weight. It broke the world sailing record in 2012 with a speed of 114 kilometres per hour (km/h). How fast is this in metres per second (m/s)?

Answer:

 114 km/h = 114 km = 114 000 m = 31.7 m/s 1 h 3 600 s

## Example Five - Converting M/S to KM/H

Change 10 m/s into km/h.

Answer:

 10 m/s = 10 m = 0.01 km = 36 km/h 1 s 0.00028 h

OR

 10 m/s = 0.01 m ÷ 1 s
 = 0.01 km ÷ 1 h = 0.01 × 3600 = 36 km/h 3600 1

## Questions

Q1. A snail travels at a constant speed of 2 cm/s. How far will it slide and slither in 1 minute?

Q2. A Mako shark, one of the world's fiercest predators, can swim 900 metres in 1 minute. How fast (in m/s) is this?

Q3. A Mako shark can detect a swimmer's heartbeat 3 metres away and it can detect sounds of movement in water hundreds of metres away. A surfer is unaware that a Mako shark is 150 metres away. How long will it take for the shark to reach the surfer?

Q4. Currently, world-class marathoners can run a marathon ( 42.195 km ) in 2 hours and 6 seconds. In the next few years, someone will break the 2 hours' mark. To do this faster time, what average speed must a marathoner run? Write your answer in m/s and km/h.

Answers
A1. 120cm
A2. 15 m/s
A3. 10 seconds
A4. 21.1 km/h, 5.9 m/s

## Maths Fun - Bob's Bicycling

It's 7 kilometres from Bob's house to his grandmother's house. It's uphill on the way there so he can only cycle at 14 km/h, but he can do 21 km/h on the way back. Bob leaves his house at 6pm. How long can Bob stop at his grandmother's house if he wants to be back home for his favourite television program at 7pm?

## Did You Know That...?

The unmanned NASA spacecraft called Voyager 1 was launched in 1977 and headed away from Earth to study our solar system. It left our solar system in 2012 and is now about 122 Astronomical Units (18 billion kilometres) from Earth. This means it is the most distant man-made object from Earth.