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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