physics paper 2 wrong

describe how radio waves are different from sound waves

describe how radio waves are different from sound waves

• are transfer

• can travel through a vacuum

• travel at speed of light

• have greater frequencies

describe features of x rays and ultrasound and what happens when they enter the body

• x rays are electromagnetic waves, very high frequencies, very high energy, short wavelength, similar size to the diameter of an atom, transverse waves, ionising radiation

• ultrasound, partially reflected when it meets a boundary between 2 different media, travel at different speeds through different media

• x rays are absorbed by bone, transmitted by tissue and skin

why better from further

• the distance from the pivot to the force is greater

• so a smaller force is required

purpose of a microphone

• to convert the pressure variations in sound vaves into various incurrent

higher speed from higher

• higher the altitude the less dense the air

• so the air resistance on the skydiver, was less

• so the skydiver able to accelerate for longer before reaching terminal velocity

why air cools faster

• at night, more radiation is emitted from the earth than absorbed from space

• cloud reflects radiation towards the earth

• at a, there is no cloud cover so a larger proportional of radiation ill be emitted into space

control variable in emission experiment

• distance between each side of the cube and the infrared detector

investigating how the speed of a wave on a stretched string depends on the tension in the string

• add or take away masses from the string

• adjust frequency using the signal generator, and/or, move the wooden rvdge

• observe a steady/stationary pattern, measure the wavelgnth

• calculate the wave speed

one similarity between the image formed by the convex and concave lens

• sim, both are diminished

• diff, concave upright, cover inverted

describe how the apparatus could be adjusted to show one complete wave without reducing the frequency

• move the wooden bridge

• to the right

field lines through a solenoid

• fiels lines going in though and out of the solenoid

• arrow pointing left/out

possible dangers caused by vehicle having a large deacceleration

• brakes overheating or lockde

• causing loss of control, or a skid

what do new observations suggest is happening to the universe

• expanding at an ever greater rate

galaxy moving towards earth

• wavelength decreases

• frequency increased

egg less likely yo bark on foam than concrete

• increase time taken to stop

• decreases rate of change in momentum

• reducing the force

from radio to gamma

• frequency increases and wave speed in air stays the same

how properties of x rays make them suitable for medical imaging of bones

• pass through soft tissue

• but absorbed by bone

emission experiment, void danger

• complete the investigation standing uop

• use slightly cooler water

• don’t touch the hot cube

explain why using a wider ray oddly give less accurate results

• it is harder to judge where the centre of a wider ray is

• causing a larger uncertainty in the measurements

ho does the size of the image change if the visitor moves further away from the security lens

• decreases

hat is meant by momentum is conserved

total momentum before = momentum after

star bigger than sun

• fusion produce new elements

• cloud of gas and dust

• pulled together by gravity

• causing increasing temperature to become protostar

• hydrogen nuclei fuse to form helium nuclei

• and the star becomes main sequence

• hydrogen begins to run out

• helium nuclei fuse to make heavier elements

• up to iron

• the star expands, red supergiant

• star collapses rapidly and explodes, supernova

• creating elements heavier than iron

• and distributing them throughout the universe

• leaving behind a neutron star or a black hole

why can a transformer be adjusted to have different number of turns on the secondary coil

• to vary the pd

• so that you don’t need a different generator for each type of device

loudspeaker orks

• current create mf around the coil

• which interacts with the permanent mf

• producing a resultant force, causing the coil/cone to move

• hen the direction of current reveres, direction of force resultant producing a sound wave

describe how the face on the pedal cases a moment about the rear axle

• the force on the pedal causes a moment bout th pedal axle

• which causes a force on th ca, which cause a moment about the rear axle

ho to determined speed of waves without measuring wavelength

• measure the distance travelled by a wave using a metre rule

• measure the time take with a timer.stopwatc

• divide the distance by the tie

why does an object appear black, blue object, red filter

• only red is transmitted by the filter

• red is absorbed by the blue objects

• so no light is reflected by the blue object

1/x curve, describe how the distance of the image from the lens decreases as the distance between the object and the lens increases

• increasing the object distance decreases the image distance more radpilky at small objects distancea

• more gradually at larger object distances

how to prove its directly proportional

• the one is straigt

• and passes through the origin

elasticit deformed

• will return to ts orignkla shape//length

• when the force is removed

factors which increase braking distance

• increased mass of car and passengers

  • increase ke of car

  • more work needs to be done to stop car

  • increases momentum of the car

• road slopes downfill

  • gravity opposes the braking force

  • resultant braking fore is reduced

problems with poor conditions of ties, brakes, road

• decreases friction

use of split rings

• provides a continuous connection between the coil and the transfoemr

• stops the wires from twisting together

why is the handle of the alternator easier to turn hen the power supply is disconnected from the transformer and lamp

• there is no induced current

• so no magnetic field produce around the coilk

• to oppose the movement of the cow

alternating current induced in alternator

• the coil moves through the magnetic field or cuts it

• a pd is induced across the coil

• there is a complete circuit, so a current is induced in the coil

• every half turn, the pd reverses direction

• so every half turn the current changes direction

explain hy the car has a maximum speed

• there is a maximum forward force provided by the motor

• as the speed of the car increases, air resistance increases

• until air resistance is equal in size to forward force

• so the car can no longer accelerate

trolley experiment, how to prevent the string from rubbing along the table

use a pulley on the edge of the bench

what happens in the electrical circuit when the car absorbs radiowaves

• alternating current induced in the electrical circuit

• with the same frequency as the radio wave

explain difference in max ke of hailstone with a mass of 10g to 20g

• kinetic energy depends on both mass and velocity

• as mass increases so does terminal velocity

• kinetic energy = m, and kinetic energy = v squared, so as mass doubles kinetic energy more than doubles

centre of mass, meaning

the point from which weight may be considered to act

whyvrefraction happens at boundary between deep and shallower water

• velocity is slower in shallow ater

• so edges of wave front entering shallow water slows down

• but the part of the ave front in deeper water continues at a higher speed, leading to a change in direction of the wave front

explain hy the velocity of the satellites changes as it orbits the earth

• force of gravity causes the satellites to accelerate towards earth

• the accelerate causes a change in direction

• velocity changes as the direction changes

what would make seismetre more sensitive

• stronger mf

• more turn on the coil;

• turns pushed closer togeher

• spring with a lower spring constant

spring experiment, source inaccuracy

• not fixing the ruler in position but simply holding the ruler next to the spring

• not clamping the ruler vertical

• misjudging the position of the bottom of the spring

• parallax error

explain why the forces on the brick at the bottom of the pool causes the brick to be stationary

• upthrust acts upwards on the brick

• normal contact force acts upwards on the brick

• weight is equal to upthrust plus normal contact force

explain why there is an ac in the output when the transform is connected to a circuit

• the ac causes a changing mf around the primary coil

• creates mg that changes direction in the core

• this induces an alternating pd across the secondary coil causing an alternating current

what makes springs suitable for use in a balance

• deforms elasticity

• so will return to its original length/shape after force is removed

• or compression is directly proportional to the force applied

• so gives a linear scale

Hyde hailstones acceleate

• there is a resultant fore acting on them

explain why if wave front travelling parallel to the bouadney between deep and shallow water, the wave front doesn’t refract at the boundary

• every point on the wave front enters the shallow water at the same time

• and so every point slows down at the same time