Physics for mod 1 2 3 yr 11

objects in motion stay in motion, objects at rest will stay at rest

F=ma

every action has an equal and opposite reaction

F = mg

Fn - w = 0
Fn = w = mg

Fn - w = ma
Fn = ma + mg

Fn - w = -ma
Fn = mg - ma

Fn - w = -ma
Fn - w = -mg
Fn = 0

Fsmax = µs x Fn

Fk = µk x Fn

Work = magnitude of force x displacement = Fxs = Fxsxcosø (cosø is the horizontal component)

W = ΔKE
the chnage in kinetic energy is equal to the net force applied on the object

E = KE + PE

KEfinal + PEfinal = KEinitial + PEinitial

1/2 mv^2

Δu = mgΔh

p = ΔE/t
p = W/t (ΔE = W) = Fs/t = Fv

p = mv

p initial = p final
maua + mbub = mava + mbvb

I = Δp = FΔt (from graph)

if I = FΔt then F = I/Δt

Total KE before = total KE after

transfer of energy through matter without the transfer of matter itself

they require a medium
electromagnetic waves do not need a medium

move prependicularly to the direction of energy

move parallel to direction of energy

v = f/λ

F = 1/T
no of waves that pass a given point in one second

the time for a complete oscilation or wavelength to occur

i=r where incident ray, reflected ray and normal lie on the same place

change in wave direction when wave speed and wavelength but not frequency

flat plane, waves reflect in same direction

rough surface, reflect in all different directions, cannot reproduce image

bending waves as they pass through a narrow opening or an object
diffraction is determined by the size of wavelenght to the size of the slit/object
e.g. wate bending around your feet at the beach

progressive: travelling left to right
standing: not moving, stationary --> when 2 waves travelling in different directions superpose, has nodes and antinodes

the angular displacement of any wave per unit of time (e.g. angle of displacement of a pendulum from it's starting position)

the specific frequency an object vibrates at is it's natural frequency
when natural angular frequency is equal to angular frequency of driving force
when a driving f is equal to natural f and is applied periodically at the same time the:
- amplitude of vibrates increases
- maximum energy from source transferred onto object

- when you go past natural frequency
- removes energy (because the object has to do work?) (usually in form of heat) and amplitude gets smaller --> e.g. bouncing basketball (PE when hits the ground and compresses and turned into KE and rebounces, every bound energy is lost as heat due to friction and deformation)
- opposite of resonance

sound is produced by vibrating objects
vibrations carried to ears, ear drums vibrates, 3 tiny bones transfer these vibrations to cochlear where hairs vibrate in fluid which are changed into an electrical signal to the brain

longitudinal wave, through a medium (generally air but travels faster through denser and solid material)

contrations: high pressure
rarefactions: low pressure
lower amplitude = less pressure in compressions

I1r1^2 = I2r2^2
inverse exponential curve
I = Power/Area (watts/m^2) (for light)

echo when sound bounces off an object
can be used to determine distance - d = 1/2 x speed of sound x time taken

1st harmonic (fundamental)
2nd harmonic (overtone 1)
3rd harmonic (overtone 2)
4th harmonic (overtone 3)

ƛ = 2L/n
f = nv/2L

ƛ = 4L/n
f = nv/4L
only odd harmonics

forced to begin on nodes (closed end) and end in antinodes (open end), thus only holds 1/4 of the wave. even harmonics demand 2 nodes or antinodes at each end which cannot exist in this tube's open-closed design

v = √T/mL^-1

where T = tension
mL^-1 = mass per unit length of string (Kgm^-1)

when 2 f with small differences in f interfere a third f results called a beat frequency (has different amplitude and frequency)
music and instrument tuners use beat f to tune

- 2 waves travel in same direction
- have same amplitude
- have same medium

fbeat = |f2-f1|

f' = f x [(vwave + vobserver)/(vwave - vsource)]
red shift when an object moves away
blue shift when an object moves towards
actual frequency is unchanged

convex lense and concave mirror (converging rays, focal point)
concave lense and convex mirror (diverging rays, virtual focus)

frequency unchanged
light travelling from less dense to more dense medium --> ray bends towards the normal, slows
light travelling from more dense to less dense medium --> ray bends away the normal, faster

n1sinø1 = n2sinø2
n2/n1 = ƛ2/ƛ1 = v2/v1 = sin(r)/sin(i) = n (relative refractive index)
nx = c/Vn --> refractive index is the ratio of speed of light in a vacuum to speed of light in a given medium

The critical angle occurs when the angle of incidence of a ray, from a more dense medium into a less dense medium, results in an angle of refraction of 90º.
sinøc = n2/n1 (less dense medium (air usually)/more dense medium)

the complete reflection of light back into its original medium when traveling from a denser to a less dense material

Dispersion refers to the separation of white light into its constituent colours (spectrum) due to the different frequencies (colours) of light in a medium, typically a transparent material like glass or water.

refraction, the bending of light as it travels from one medium to another. However, not all wavelengths of light bend by the same amount. In most transparent materials, shorter wavelengths (blue and violet) refract more than longer wavelengths (red and yellow). This differential refraction is what causes light to spread out into its constituent colours.

frequency of a force driving an oscillating system

frequency a system will naturally oscillate at wihtout driving or dampening forces

frequency
amplitude