# Basic Physics AS REvision Notes (Mechanics, Materials, and Waves)

Basically all of the **key** notes and formulae needed for tomorrows exam, **not** hugely in depth but highlights topics for revision. Enjoy!

- Created by: Ollie
- Created on: 19-01-12 17:10

First 433 words of the document:

Physics Revision

Superposition- The resultant displacement at any point is found by adding displacement

amplitudes.

Interference- Constructive: Two sources in fixed phase, path difference is an even

number of half wavelengths.

Destructive: Two sources in fixed phase, path difference is an odd number

of half wavelengths.

Coherent- Two sources are coherent if the waves emitted from them are phase-linked

i.e. zero phase difference, therefore must have the same frequency.

Diffraction- Increase slit width =brighter

=fewer fringes

More slits = Max brighter- more light

Max sharper- constructive interference only happens at certain

precise directions

Conditions for equilibrium- The vector sum of the forces must be zero

The sum of the moments about a point must be zero

Moment- Is the product of force and perpendicular distance from the line of action of the

force to the pivot

Equilibrium (principle of moments)- Clockwise moments = anticlockwise moments

Couple- Is the product of one force and the perpendicular distance between the lines of

action of the forces.

Area under VT graph is distance travelled

Throwing objects- a= -g when going up

v= 0 at top of flight

u= 0 if dropped

Know: v= final velocity

u= initial velocity

s= displacement

t= time

a= acceleration= g= gravity= 9.81 unless otherwise listed

Formulae: v=u+at

v^2=u^2+2as

s=ut+1/2at^2

s=(u+v/2)t

Learn: v=s/t

a=change in v/change in t

Newtons first law- "Every object in a state of uniform motion tends to remain in that

state of motion unless an external force is applied to it"

Newtons second law- "Force is proportional to the rate of change of momentum" F=MA

Newtons third law- "For every action there is an equal and opposite reaction"

Work- Force x displacement in line of action of the force W=Fs x sin theta

Power- Rate of doing work P=W/T and the product of force and velocity P=FV

Energy- Ep=mxgxh

Ek=1/2xmxv^2

Ep top = Ek bottom assumes no energy is lost due to friction as heat

Therefore v=sqrt(2xgxh)

Density- mass/ volume

Hookes law- F=ke k= spring constant e=extension

Force y by extension x graph steeper the gradient, stiffer the material

Are under force by extension graph is elastic strain energy E=1/2xFxe

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