# 5.6.2 Speed

### Speed

• The speed of an object is the distance it travels every second
• Speed is a scalar quantity
• This is because it only contains a magnitude (without a direction)
• The average speed of an object is given by the equation:

• Distance is measured in metres, m
• Time is measured in seconds, s
• Speed is therefore measured in metres per second, m/s

A hiker might have an average speed of 2.0 m/s, whereas a particularly excited bumble bee can have average speeds of up to 4.5 m/s

#### Exam Tip

Remember that average speed is the mean speed of the moving object.

Its speed at a specific moment could be higher or lower – so because the speed changes you need to consider the total distance and time taken.

### Non-Uniform Motion

• The speed of an object is rarely constant
• Hikers change their pace continuously as they walk
• Bumblebees buzz around in all directions with varying speed
• Cars are constantly speeding up and slowing down throughout a journey
• Non-uniform motion refers to motion that is changing
• Changing motion can mean the object is changing its speed, direction or both

Race drivers know all about non-uniform motion, especially slowing down for corners and speeding up on the straight sections of track

### Author: Jonathan

Jonathan graduated with a first-class Master's degree in Theoretical Physics from Imperial College London. He has worked in education for more than a decade as a Maths and Physics Teacher, Tutor, Head of Physics, and most recently, as Assistant Headteacher. He is now an Educational Consultant and works with us to design and improve our Physics resources.
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