GCSE Physics revision

Scalar and vector quantities

Forces and their interactions

AQA 4.5.1.1

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AQA student objectives

Learning pathway

ALL 🎯

Scalar quantities have magnitude only.

MOST 🎯🎯

Apply the specified scientific knowledge of scalar and vector quantities to a relevant example.

SOME 🎯🎯🎯

Analyse an unfamiliar example of scalar and vector quantities using the specified scientific ideas.

Revision summary

Read on screen, then print for Cornell-style active revision.

Scalar quantities have magnitude only (size or extent), whereas vector quantities have both magnitude and a direction.
Speed is a scalar quantity because it only describes how fast something is moving, with no direction stated.
Velocity is a vector quantity because it includes both the magnitude of motion and a direction, such as 55 m/s east.

1. Scalar and Vector QuantitiesAQA

Scalar quantities have magnitude only (size or extent), whereas vector quantities have both magnitude and a direction.
Speed is a scalar quantity because it only describes how fast something is moving, with no direction stated.
Velocity is a vector quantity because it includes both the magnitude of motion and a direction, such as 55 m/s east.

Distance is a scalar quantity, describing how far an object has travelled with no reference to direction, e.g. 40 m.
Displacement is a vector quantity, describing how far an object has moved from its starting point in a specific direction, e.g. 40 m east.
The key difference is that displacement accounts for direction, making it more informative than distance alone.

2. Distance and DisplacementAQA

Distance is a scalar quantity, describing how far an object has travelled with no reference to direction, e.g. 40 m.
Displacement is a vector quantity, describing how far an object has moved from its starting point in a specific direction, e.g. 40 m east.
The key difference is that displacement accounts for direction, making it more informative than distance alone.

Speed is calculated using the formula: s = dt , where s is speed, d is distance, and t is time.
For example, a train crossing a 550 m bridge in 10 seconds has a speed of 550
10 = 55 m/s.
The result is a scalar quantity, so no direction is included in the answer.

Velocity is calculated using the formula: v = st , where v is velocity, s is displacement, and t is time.
Using the same train example with a displacement of 550 m east, the velocity would be
55 m/s east.
A negative velocity can be used to represent motion in the opposite direction, such as travelling backwards.
In both equations, t always represents time, but s represents displacement in the velocity equation and speed in the speed equation.

4. Calculating VelocityAQA

Velocity is calculated using the formula: v = st , where v is velocity, s is displacement, and t is time.
Using the same train example with a displacement of 550 m east, the velocity would be
55 m/s east.
A negative velocity can be used to represent motion in the opposite direction, such as travelling backwards.
In both equations, t always represents time, but s represents displacement in the velocity equation and speed in the speed equation.

Objects often do not travel at a constant speed, so their speed varies throughout a journey.
Average speed is calculated by dividing the total distance by the total time taken for the entire journey.
Average velocity is calculated by dividing the total displacement by the total time taken for the entire journey.

5. Average Speed and Average VelocityAQA

Objects often do not travel at a constant speed, so their speed varies throughout a journey.
Average speed is calculated by dividing the total distance by the total time taken for the entire journey.
Average velocity is calculated by dividing the total displacement by the total time taken for the entire journey.

A person walks at approximately 1.5 m/s, runs at around 3 m/s, and cycles at about 6 m/s.
A car on a main road travels at around 25 m/s, a fast train at approximately 55 m/s, and a plane can exceed 250 m/s.
These values can vary depending on factors such as age, health, and effort for people, or road and weather conditions for vehicles.

6. Typical Speeds of People and VehiclesAQA

A person walks at approximately 1.5 m/s, runs at around 3 m/s, and cycles at about 6 m/s.
A car on a main road travels at around 25 m/s, a fast train at approximately 55 m/s, and a plane can exceed 250 m/s.
These values can vary depending on factors such as age, health, and effort for people, or road and weather conditions for vehicles.

Sound waves travel at 330 m/s through air — this is a key value you need to remember for your GCSE exams.
The speed of sound changes depending on the medium it travels through, for example it travels faster through water than air.
Wind speed varies from nearly 0 m/s on a calm day to speeds exceeding that of a fast train during severe weather.
Wind speed is affected by factors such as temperature, atmospheric pressure, and physical structures like buildings or mountains.

7. Speed of Sound and WindAQA

Sound waves travel at 330 m/s through air — this is a key value you need to remember for your GCSE exams.
The speed of sound changes depending on the medium it travels through, for example it travels faster through water than air.
Wind speed varies from nearly 0 m/s on a calm day to speeds exceeding that of a fast train during severe weather.
Wind speed is affected by factors such as temperature, atmospheric pressure, and physical structures like buildings or mountains.