# Speed, distance and time

is how far an object moves. It does not include an associated direction, so distance is a quantity.

is the of distance - it is the distance travelled per unit time. Like distance, speed also does not have an associated direction, so it is a scalar quantity.

### Typical speeds

When people walk, run, or travel in a car their speed will change. They may speed up, slow down or pause for traffic. The speed at which a person can walk, run or cycle depends on many factors including:

• age
• terrain
• fitness
• distance travelled

Some typical values for speed in metres per second (m/s) include:

Method of travelTypical speed in m/s
Walking1.5
Running3
Cycling6
Car13-30
Train50
Aeroplane250

It is not only moving objects that have varying speed. The speed of the wind and the speed of sound also vary. A typical value for the speed of sound in air is about 330 m/s.

### Calculations involving speed, distance and time

The average speed of a moving object can be calculated using the equation:

This is when:

• average speed (v) is measured in metres per second (m/s)
• distance travelled (s) is measured in metres (m)
• time (t) is measured in seconds (s)

### Example

A car travels 500 m in 50 s, then 1,500 m in 75 s. Calculate its average speed for the whole journey.

First calculate total distance travelled:

Then calculate total time taken:

Then use

To find v:

## Converting units

It is important in motion calculations to be able to easily convert between units, in particular between metres and kilometres, and seconds and hours.

1 metre is equal to 0.001 kilometres so to convert from metres to kilometres - divide by 1,000.

1 kilometre is equal to 1,000 metres so to convert from kilometres to metres - multiply by 1,000.

1 hour is equal to 3,600 seconds so to convert from hours to seconds - multiply by 3,600.

For example:

Question

Convert the following into kilometres:

1. 12,300 m
2. 5,389 m
3. 252 m
4. 64 m

1. 12,300 m = 12.3 km
2. 5,389 m = 5.389 km
3. 252 m = 0.252 km
4. 64 m = 0.064 km
Question

Convert the following into seconds:

1. 1.5 h
2. 12 h
1. 1.5 h = 5,400 s
2. 12 h = 43,200 s
Question

Convert 1 m/s into km/h.

1. 1 m/s = 3,600 m/h
2. 3,600 m/h = 3.6 km/h