# Velocity

## Contents

## Key Stage 3

### Meaning

Velocity is very similar to speed but it includes the direction an object is moving.

## Key Stage 4

### Meaning

Velocity is a vector quantity describing the speed and direction of a moving object.

### About Velocity

- Velocity is a scalar because it has magnitude and direction.
- The SI Unit for the magnitude of velocity is metres per second (m/s).
- Velocity is different from its scalar counterpart 'speed' because speed does not include the direction of travel.
- The velocity of an object can change while the speed remains constant.

### Equation

Velocity = (Displacement) / (time)

\(v = \frac{s}{t}\)

Where

\(v\) = Velocity of the object.

\(s\) = The displacement between the starting point and end point of a journey.

\(t\) = The time taken between the two points.

### Example Calculations

A wave travels 1000m in a time of 12.5s. Calculate the magnitude of the velocity of the wave correct to two significant figures. | The Moon is approximately 390,000km away from the Earth. It takes a Radio Wave 1.3 seconds to travel that distance. Calculate the magnitude of the velocity of the Radio Wave correct to two significant figures. | An alpha particle can travels around 6cm from a source taking 4.0ns before colliding with an air molecule. Calculate the magnitude of its velocity on this journey correct to two significant figures. |

1. State the known quantities
s = 1000m t = 12.5s |
1. State the known quantities
s = 390,000km = 390,000,000m t = 1.3s |
1. State the known quantities
s = 6cm = 0.06m t = 4.0ns = 4.0 x 10 |

2. Substitute the numbers into the equation and solve.
\(v = \frac{s}{t}\) \(v = \frac{1000}{12.5}\) \(v = 80m/s\) |
2. Substitute the numbers into the equation and solve.
\(v = \frac{s}{t}\) \(v = \frac{390000000}{1.3}\) \(v = 300,000,000m/s\) |
2. Substitute the numbers into the equation and solve.
\(v = \frac{s}{t}\) \(v = \frac{0.06}{4.0 \times 10^{-9}}\) \(v = 15,000,000m/s\) |

### References

#### AQA

*Velocity, pages 117, 148, GCSE Physics, Hodder, AQA**Velocity, pages 136-141, 144-155, 157, GCSE Physics; Third Edition, Oxford University Press, AQA**Velocity, pages 141, 143, 146-9, 182-3, GCSE Physics; Student Book, Collins, AQA**Velocity, pages 147, 178-180, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA**Velocity, pages 147-149, GCSE Combined Science Trilogy; Physics, CGP, AQA**Velocity, pages 207, 226, GCSE Combined Science Trilogy 2, Hodder, AQA**Velocity, pages 208, 210, 211, GCSE Combined Science; The Revision Guide, CGP, AQA**Velocity, pages 60, 61,62, GCSE Physics; The Revision Guide, CGP, AQA*

#### Edexcel

*Velocity, page 22, GCSE Physics, CGP, Edexcel**Velocity, pages 12, 13, 15, 17, 106, GCSE Physics; The Revision Guide, CGP, Edexcel**Velocity, pages 145, 146, 148, 150, 210, GCSE Combined Science; The Revision Guide, CGP, Edexcel**Velocity/time graphs, page 148, GCSE Combined Science; The Revision Guide, CGP, Edexcel**Velocity/time graphs, page 15, GCSE Physics; The Revision Guide, CGP, Edexcel**Velocity/time graphs, pages 30-32, GCSE Physics, CGP, Edexcel**Velocity/time graphs, pages 8-9, GCSE Physics, Pearson Edexcel**Velocity; distance/time graphs, pages 27, 28, GCSE Physics, CGP, Edexcel*

#### OCR

*Velocity, pages 157, 159, 162, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR**Velocity, pages 21, 22, 25, 29, Gateway GCSE Physics; The Revision Guide, CGP, OCR**Velocity; And acceleration, pages 51, 53, Gateway GCSE Physics, Oxford, OCR**Velocity; And speed, pages 50, Gateway GCSE Physics, Oxford, OCR**Velocity; Calculation, pages 55, 58, Gateway GCSE Physics, Oxford, OCR**Velocity; Terminal velocity, pages 70, Gateway GCSE Physics, Oxford, OCR**Velocity; velocity-time graphs, pages 56-57, Gateway GCSE Physics, Oxford, OCR*