physics paper 2

acceleration

rate of change of velocity

displacement

how far an object moves in a given direction

elastic potential energy

the energy stored in a spring when it is stretched or compressed due to the work done on the spring by the deforming force it is equal to the work done as long as the object does not plastically deform

limit of proportionality

point beyond which the extension of an elastic object is no longer directly proportional to the force applied to it

moment

the turning effect of a force, equal to the product of the magnitude of the force and the perpendicular distance from the pivot to the line of action of the force

magnitude

size of a physical quantity

scalar and vector quantities where v is magnitude and direction

newtonmeter

spring balance used to measure weight

newtons law 1

if a stationary objects resultant force is zero the object will remain stationary and if a moving objects resultant force is zero the object will continue to move at the same speed and in the same direction

resultant force

single force that can replace all the individual forces acing on an object and have the same effect

scalar quantity

quantities that only have a magnitude not a direction

spring constant

measure of a springs stiffness. the higher the spring constant the smaller the extension is for a given force

vector quantities

quantities that have both a magnitude and direction

velocity

a vector quantity that is a measure of the rate of change of displacement it is the speed in a given direction

amplitude of a wave

distance from the equilibrium line to the maximum displacement crest or trough

wave frequency

number of waves that pass a single point per second

transverse wave

light or any electromagnetic wave vibrations are at right angels to the direction of travel

longitudinal waves

sound waves vibrations are in the same direction as the direction of travel

electromagnetic waves

are transverse waves and do not need particles to move. In space all waves have the same velocity

1. radio

2. microwave

3. infrared

4. visible

5. ultraviolet

6. x ray

7. gamma ray

visible light

our retina can only detect visible light it is near the middle of the electromagnetic spectrum and has longish wavelength and high ish frequency

refraction

when light enters a denser material than air it bends

substances will absorb transmit refract or reflect certain EM waves depending on wavelength

glass will transmit and refract visible light

when light enters a denser material it slows down shorter wavelengths slow down more than longer wavelengths eg blue light slowing down more than red

radio waves

produced by oscillations in electrical circuits

hazards of UV and X ray

effect human body tissue can cause cancer the effects depend on the type of radiation and the size of the dose

UV- skin ages prematurely increasing the risk of skin cancer
X ray- and gamma are ionising that can cause mutations of genes and denaturing healthy cells causing cancer

radio waves can be used for

long wavelength and can travel far without losing quality therefore used for TV and radio

micro waves can be used for

satellite communication and cooking food

can penetrate atmosphere to reach satellites

permanent magnet

always magnetic always have poles produces its own magnetic field

induced magnets

becomes magnetic when placed in a magnetic field

materials that are magnetic but don’t have fixed poles

they can be made into temporary magnets by using a permanent magnet

iron nickel cobalt

magnetic fields

field lines point from north to south and strength decreases with distance from magnet

always from north to south

use plotting compasses to see this

the earths core

is magnetic and creates a large magnetic field around the earth

current

produces a magnetic field around a wire direction dictated by right hand grip rule

greater the current stronger the magnetic field

flemings left hand rule

thumb is force pointy finger is field middle finger is current

how do electric motors work

permanent magnets lie in fixed position and there is a coil of current carrying wire

it rotates because one side is moved up and the other side where current is flowing in the opposite direction moves down

what type of force is exerted if two like poles of a magnet are brought near each other

a repulsive non contact force

magnetic field

region surrounding a magnet where another magnet or magnetic material experiences a non contact force

magnetic materials

1. Iron

2. Steel

3. cobalt

4. nickel

solenoid

coil of wire which when current passes through creates a strong magnetic field

what is a force

a push or pull acting on an object due to an interaction with another object

there are contact(friction air resistance tension) and non contact forces (gravitational forces electrostatic forces magnetic forces)

weight

force that acts on an object due to gravity and the objects mass

newtons are the unit used

work done

force multiplied by distance

inelastic deformation

a deformation which results in the object being permanently stretched the object doesn’t return to its original shape when the force is removed

speed of sound

330 m/s

F=ma

resultant force is mass multiplied by acceleration

stopping distance of a vehicle

the sum of thinking distance and braking distance
the stopping distance is increased with an increase in speed

energy transfers when a car applies its brakes

work is done by the friction force between the brakes and wheel

kinetic energy of the wheel is converted to heat and is dissipated to the surroundings through the brake discs

RQ to determine the correlation between the mass placed on a spring and the spring extension by measuring resultant spring lengths

1. set up so the spring will return to original dimensions if stretched within its elastic limit

2. attach pointer to base of the spring

3. measure initial length of spring without any weights attached

4. addd 10g mass to the base of the spring and record the length of the spring

5. repeat and continue to add masses ensuring that the spring doesn’t oscillate after each weight

6. calculate the extension of the spring for each mass by subtracting the initial length of the spring from each different length of the spring

for safety ensure stand is secure
wear safety glasses in case the spring snaps

hookes law

the extension of an elastic object is directly proportional to the force applied provided the limit of proportionality is not exceeded