# basic physics unit 1

- Created by: charlotte j300
- Created on: 21-09-18 10:55

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- basic physics unit 1.1
- units and dimentions
- there are 6 base units that i need to know
- Kilogram Kg
- metre m
- second s
- ampere A
- kelvin K
- mole mol

- Homogeneous-units are equal on both sides of an equation
- SI units; divide by 1000 to increase eg. 1m to 0.001km and multiply by 1000 to decrease eg. 1g to 1000mg

- there are 6 base units that i need to know
- density
- density is constant and doesn't depend on the shape or size of the the sample of material
- the equation is p=m/v
- the units are kgm^-3

- moments
- definition= the moment of a force about a point is the product of the force and the perpendicular distance from the point to the line of action of the force
- moment F about P = Fd
- use this to work out moments
- the units are Nm

- moment F about P = Fd
- the principle of moments= the sum of the clock wise = sum of the anti clock wise
- conditions of an equilibrium; no resultant moment and no resultant force
- use trig to work out moments
- single support problems; use trig
- two support problems; use the sum of ac= sum of cw ; take moments from s1 to find s2 and vice-versa

- definition= the moment of a force about a point is the product of the force and the perpendicular distance from the point to the line of action of the force
- scalars and vectors
- scalar= magnitude only vector= magnitude and direction
- to add vectors and find the resultant force use Pythagoras or simple trigonometry
- resolving vectors= use trigonometry

- centre of gravity
- the centre of gravity of a body is the point where the entire weight of the body can be considered to act
- for symmetrical bodies the centre of gravity must lie on any plane of symmetry

- units and dimentions

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