Scalars & Vectors (AQA AS Maths): Revision Note
Exam code: 7356
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Scalars & vectors
Mechanics uses a variety of different scalar and vector quantities.
What are scalars?
- Scalars are quantities without direction, they only have a size (magnitude) - e.g. a speed of 7 m/s, a distance of 5 m, a time of 15 s or a mass of 12 kg 
 
- Scalars can only be positive- you can’t have a negative distance or speed! 
What are vectors?
- Vectors are quantities which also have a direction, this is what makes them more than just a scalar - e.g. two objects with velocities of 7 m/s and ‑7 m/s are travelling at the same speed but in opposite directions 
 
- Vector quantities can have positive or negative components 
- Some examples of vector quantities you may come across are displacement, velocity, acceleration, force/weight, momentum - Displacement is the distance moved in a given direction from a starting point 
- Velocity is a speed in a given direction (displacement over time) 
- Acceleration is the change in velocity over time 
 

Vector quantities of displacement, velocity and acceleration
Worked Example
State whether each of the following is a scalar or a vector quantity.
a) A speed boat travels at 3m/s on a bearing of 052o
b) A garden is 1.7 m wide
c) A car accelerates at 5.4 ms-2
d) A film lasts 2 hours 17 minutes
e) An athlete runs at an average speed of 10.44 ms-2
f) A ball rolls forwards 60 cm before stopping

Examiner Tips and Tricks
- Make sure you fully understand the definitions of all the words in this section so that you can be clear about what your exam question is asking of you 
- Vectors appear in bold (non-italic) font in textbooks, on exam papers, etc (i.e. F, α ) but in handwriting should be underlined (i.e. F , α ) 
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