Edexcel A Level Maths: Mechanics:复习笔记1.1.1 Scalars & Vectors

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

Exam Tip

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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