# MECHANICS, MATERIALS & WAVES PHYA2 Revision

for the AQA Unit 2 PHYA2 specification

- Created by: Student123
- Created on: 11-03-11 00:32

First 178 words of the document:

MECANICS 7.1 8.8

MECHANICS

Scalars and vectors

· A scalar has only magnitude

o mass, temperature, time, length, speed and energy

· Vector quantities have both magnitude and direction

o displacement, force, velocity, acceleration and momentum

· Resultant Vectors

o Magnitude = Pythagoras

o Direction = Trigonometry

· Resolving Vectors

o Horizontal component = F x = F cos

o Vertical component = F v = F sin

Moments

The moment is the turning effect produced by a force:

o Moment of a force about a point (in N m) = force (N) x perpendicular distance from

the force to the point (m)

A couple is the turning effect due to two equal forces acting in the opposite direction:

o Couple (in N m) = magnitude of one force (N) x perpendicular distance between the

two forces in the couple (m)

The principle of moments states that, for an object in equilibrium:

o Sum of the clockwise moments about a point = sum of anti-clockwise moments

about that point.

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