Physics Paper 1: Topics 1-6 Flashcards Preview

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Flashcards in Physics Paper 1: Topics 1-6 Deck (93):

Equation for distance travelled for an object travelling at a constant speed

Distance travelled (m) = (average) speed (m/s) x time (s)
d = s x t


What is the speed of sound in air

340 m/s


What is acceleration, what is meant by uniform acceleration?

Acceleration is how quickly you’re speeding up (change in velocity over time) and uniform acceleration means constant acceleration


Equation for average acceleration

Acceleration (m/s^2) = (final velocity - initial velocity (m/s) ) / time (s)

a = (v-u)/t


What is acceleration due to gravity near earths surface

Roughly 10m/s^2


Equation for uniform acceleration.

Final velocity ^2 (m/s) - initial velocity ^2 = 2 x acceleration x distance


On a distance time graph, what does __ tell you:
- gradient at any point (if gradient curved, use a tangent)
- flat
- steeper gradient
- curves
-increasing gradient
-decreasing gradient

- gradient at any point gives the speed of the object
- flat = object has stopped
- steeper graph, object travelling faster
- curves represent acceleration
- increasing gradient, object speeding up
- decreasing gradient, object slowing down


On a velocity time graph, what does __ tell you:
- gradient at any point (if gradient curved, use a tangent)
- flat
- steeper gradient
-positive gradient
- curves
-straight line / and \
- area under graph

Gradient, acceleration
Flat section, steady speed
Steeper graph, greater acceleration or deceleration
Positive gradient, acceleration. Negative gradient, deceleration.
Curve, a changing acceleration
Straight line, / constant acceleration, \ constant deceleration
Area under graph, distance travelled in that time interval


What is Newton’s first law

Resultant force is needed to make something start moving, speed up or slow down, a non zero resultant force always produces acceleration in the direction of the force


What is Newton’s second law

Force and acceleration are directly proportional. Acceleration is inversely proportional to mass of an object.


Equation for resultant force

Resultant Force (N)= mass (kg) x acceleration (m/s^2)

F = m x a


What is equation for weight of an object

Weight (N) = mass (kg) x gravitational field strength (N/Kg)

W = m x g

G = 10 N/Kg on Earth


What is velocity?

Speed and direction of an object


What’s centripetal force?

Force that keeps something moving in a circle. Happens when object moving at constant speed is constantly changing direction, so constantly changing velocity, and so accelerating. Therefore must have a resultant force, which acts towards centre of circle


What’s Inertia? What’s an objects inertial mass?

Tendency for motion to remain unchanged (specifically velocity)

Inertial mass is how difficult it is to change the velocity of the object . The ratio of force over acceleration.


Equation for inertial mass

Inertial mass = force / acceleration


What’s Newton’s third law?

When two forces interact the forces they exert on each other are equal and opposite

Eg book on table: two normal contact forces against each other PLUS Weight due to gravity from Earth vs book pulling back up on Earth


Equation for momentum

Momentum (kg m/s) = mass (kg) x velocity (m/s)

P = m x v


How are changes in momentum caused?

When a resultant force acts on an object for a certain amount of time, it causes change in momentum


Equation for change in momentum

Force (N) = change in momentum (final momentum - initial momentum) (kg m/s) / time (s)

F = (mv-mu) / t


Equation for stopping distance

Stopping distance = thinking distance (affected by drivers reaction time and speed) + braking distance (affected by speed, conditions of breaks etc)


What are the eight energy stores

Kinetic, anything moving
Chemical, anything releasing energy through chemical reaction
Gravitational potential, anything in a gravitational field
Elastic potential, anything stretched
Electrostatic, two charges that attract or repel each other
Magnetic, two magnets
Nuclear, atomic nuclei release energy from this store in nuclear reactions


Equation for kinetic energy in an objects kinetic energy store

Kinetic energy (J) = 0.5x mass (kg) x (speed)^2 (m/s^2)

KE = 1/2 x m x v^2


Equation for change in gravitational potential energy in an objects gravitational potential energy stores

Change in gravitational potential energy (J)= mass (kg) x gravitational field strength (N/Kg) x change in vertical height (N/Kg)

Triangle GPE = m x g x triangle h


What are the four main ways of energy transfer between stores

Mechanically: force acting on object and doing work
Electrically: charge doing work against resistance
By heating: energy transferred from hotter to colder object
By radiation: energy transferred by waves


What does it mean when energy is dissipated

Energy is spread out and lost


What is the equation for total energy input

Total energy input = useful energy output + wasted energy


What’s the equation for the efficiency of a device?

Efficiency = useful energy transferred by device (J) / total energy supplied by device (J)

Times answer by 100 to get as a percentage


How does lubrication reduce unwanted energy transfers?

Reduces energy transferred by friction


Explain how conduction works

One side of object heats, particles vibrate more, collide with each other. Energy transferred from particles kinetic energy store to other particles, which then vibrate faster (energy transfers though the object)


What is thermal conductivity

How well a material transfers energy by conduction


What are bio fuels?

Renewable energy resources created from either plant products or animal dung


How does hydro electricity work?

Flooding valleys by building big dams, rain water caught and allowed out through turbines


How do tidal barrages work?

Big dams built across river estuaries with turbines in. Tide comes, fills estuary, water let our through turbines at a controlled speed.


What experiment do you use to investigate motion?

Trolley on ramp test
Can use this to test affect of Trolley’s mass and investigate effects of accelerating force
^ force and acceleration are proportional, mass and acceleration are inversely proportional


What experiment can be used to measure reaction time

Ruler drop experiment

Longer distance ruler falls = longer reaction time


What does a wave do?

I travels through a medium, causing particles in the medium to vibrate and transfer energy and information between each other. Overall, the particles stay in the same place,


What’s amplitude of a wave?

Displacement from rest position to a crest or a trough


What’s wavelength of a wave?

Length of a full cycle of a wave (eg from crest to crest)


What’s frequency of a wave

Number of complete cycles of a wave passing a certain point per second. Measured in Hertz, hz

1 hz = 1 wave per second


What’s the period of a wave

Number of seconds it takes for one full cycle


What’s equation to work out the period of a wave?

Period = 1/frequency


What’s a transverse wave?

Wave where vibrations are perpendicular (90*) to the direction the wave travels
(Vibrations up and down)

Eg: electromagnetic waves, waves in water, S-waves


What are longitudinal waves

Vibrations are parallel to direction wave travels
(Vibrations left to right)
Cause compressions in the mediums they pass through

Eg: sound waves, p-waves


What’s a compression and what’s a refraction?

Compressions are points where the wave is high pressure, with lots of particles
Rarefactions are points where the wave is low pressure, with fewer particles


What’s wave speed?

How quickly a wave moves through space


What are the two equations for wave speed?

Wave speed = frequency (Hz) x wavelength (m)

Wave speed (m/s) = distance (m) / time (s)


What is the experiment for measuring speed of sound waves

Use an oscilloscope to measure speed of sound

Attaching signal generator to speaker allows you to generate sound at a specific frequency. Use two microphones and an oscilloscope to find the wavelength of the sounds generated.


What is the experiment for measuring speed of water waves

Measure speed of water ripples using a strobe light. Use signal generator attached to dipper of ripple tank to create water waves at a set frequency. Frequency of strobe lights and waves are same when waves appear to stop moving.


What is the experiment for measuring speed of waves in solids

Use peak frequency
Measure frequency of sound waves produced when you hit the object, sound waves produced around object have same frequency as waves produced in the object


What’s a material interface?
What three things can happen when a wave meets a material interface

A boundary between two materials

- wave absorbed by second material
- wave transmitted through second material (carries on travelling through)
- wave reflected, incoming ray sent back away from second material


What’s refraction

Wave hits boundary at an angle, the change of speed between materials due to different densities of materials causes a change in direction of wave
- slows down, bends towards normal

EM waves tend to slow down in denser materials


On a ray diagram what is:

- the normal
- the angle of incidence
- angle of refraction
- how are the ‘rays’ shown

- normal, imaginary line perpendicular to the point incoming wave hits boundary
- incidence, angle between incoming (incident) ray and normal
- refraction, angle between refracted ray and normal
- rays are shown as straight lines perpendicular to the wave fronts


What’s the experiment to investigate refraction

Use transparent materials. Use a ray box to produce thin ray of visible light to be refracted


What are electromagnetic waves?

Transverse waves. Vibrations of electric and magnetic fields, can travel through a vacuum. Generated by a variety of changes in atoms in their nuclei, therefore have a large range of frequencies

EM waves transfer energy from a source to an absorber. Higher frequency > greater energy transferred


List the EM spectrum. Which end has longest wavelengths? Which end has highest frequency? Which ones are ionising radiation? Which ones cause heating?

Radio waves (long wavelengths, low frequency)
Microwaves (cause heating)
Infrared (cause heating)
Visible light
Ultra violet (ionising - cause mutations)
X-rays (ionising)
Gamma rays (ionising) (short wavelength, high frequency)


Describe how EM waves are produced

EM waves are made of oscillating electric and magnetic fields. Alternating currents are made up of oscillating charges, so when charges oscillate they produce EM waves with the same frequency as the alternating current.


What’s a transmitter?

Object in which charges (electrons) oscillate to produce radio waves


How are microwaves used?

For communication, they’re passed through earth’s watery atmosphere
For microwave ovens, they are absorbed by water molecules in food


How is Infrared radiation produced and how’s it used?

All hot objects give out IR radiation. Hotter object, more IR.
Thermal imaging: infrared cameras detect IR, turns it into electric signal, which is displayed on a screen as a picture
IR can transfer information eg in phones/tv remotes


What’s a use of visible light

Photographic film reacts to visible light and films an image
Digital camera contains image sensors, detects visible light, generates electrical signal, converts into image


What’s a use of ultraviolet

Used in fluorescent lamps. Fluorescent chemicals absorb UV, emit visible light


What’s a use of X-rays

Make image show up on photographic film
Radiographers take X-ray images: X-rays transmitted by flesh, absorbed by denser material eg bone. Create negative image.
Used in airport security scanners to detect hidden objects


What’s a use of gamma rays

Used for sterilisation, kill microbes
Used in cancer treatment
Some medical imaging techniques use gamma to detect cancer


What’s guess of overall size of an atom


(Sizes for atoms always written in negative form)


What do atoms form?

Atoms join together to form molecules


Relative mass and relative charge of proton, neutron and electron?

Proton: mass 1, charge +1
Neutron: mass 1, relative charge 0
Electron: mass 0.0005, charge - 1


What’s ionising radiation?

Any radiation that can knock an electron from an atom by absorbing the radiation, which has enough energy to move the atom out all the electron shells


What’s the atomic number tell you?

The number of protons


What’s the mass (nucleon) number tell you.?

Number of protons + neutrons


If an element is written as ‘carbon-14’ what does the 14 mean?

14 is the mass number, has 14 protons + neutrons


What’s an isotope.

isotopes of an element are atoms with the same atomic number but a different mass number. All elements have multiple isotopes, usually only a few are stable.


What’s radioactive decay?

Where unstable isotopes decay into other elements and give out radiation as they try to become more stable.

Radioactive substances emit one or more type of ionising radiation during decay


Summarise alpha radiation

An alpha particle emitted from a nucleus. Alpha particle has 2 neutrons and 2 protons (like a helium nucleus)
They don’t penetrate far and are stopped quickly. Can travel a few cm in air, absorbed by a thin sheet of paper. Are strongly ionising (due to their size)


Summarise beta radiation

Beta particles can be electrons or positrons
B- particle is a fast moving electron released by nucleus. Have virtually no mass and a relative charge of -1
B+ particle is a fast moving positron (same mass as electron, +1 charge)

Both are moderately ionising. B- move a few meters in air, absorbed by 5mm thick aluminium sheet. B+ has a smaller range


What’s annihilation?

When a positron hits and electron, the two destroy each other and produce gamma rays


Summarise gamma rays

Nucleus decayed, undergoes nuclear rearrangement and releases some energy. Gamma rays are waves of EM Radiation released by nucleus. They carry away this released energy.

Travel for a long distance in air. Penetrate far into materials. Absorbed by thick lead sheets or metres of concrete. Weakly ionising as usually pass through rather than collide with atoms


What do nuclear equations do? How are they structured

They show the radioactive decay by using element symbols. Total mass and atomic numbers must be equal on both sides

Atom before decay > atom after decay + radiation emitted


What does alpha decay do to an atom in a nuclear equation?

Mass number decreases by 4, atomic number decreases by 2


What does beta minus decay do to an atom in a nuclear equation?

Mass number doesn’t change, atomic number +1


What does positron emission do to an atom in a nuclear equation?

Mass number doesn’t change, atomic number -1
In alpha and beta emissions, new element formed due to change in atomic number


What does neutron emission do to an atom in a nuclear equation?

Mass number -1, atomic number stays the same


What does gamma emission do to an atom in a nuclear equation?

Mass and atomic numbers stay the same


What are radioactive sources?

Contain radioactive isotopes which give out radiation from nucleus of atoms. This is a random process


What’s activity (in radiation)

Rate at which the source decays. Measured in Becquerels, Bq.
1 Bq = 1 decay a second

Radioactive nucleus decay one by one, this activity never reaches zero


What two items can be used to measure activity of a radioactive source

A Geiger Müller Tube: clicks every time it detects radiation. Can attach it to a counter
Photographic film: more radiation > film gets darker


What’s half life?

The average time taken for number of radioactive nuclei in isotope to halve

Short half life > activity falls quickly > nuclei very unstable, rapidly decay
^ very dangerous at start, quickly becomes safe


How do you plot a graph to show radioactive activity, How do you find half life on this graph

Plot graph of activity against time (take into account background radiation)

Half life = time interval on bottom axis corresponding to a halving of activity on a vertical axis


What’s background radiation?

Low level radiation that’s around us all the time. Comes from radioactivity of naturally occurring unstable isotopes, eg air, food, rocks


What are cosmic rays?

Radiation from space. Mostly comes from the sun. Earths atmosphere protects us from most of this


What’s the ‘absorbed radiation dose’ mean?

The amount of radiation you’re exposed to (amount of energy your body absorbs)
Varies depending on where you live


What does it mean if something’s irradiated

Object exposed to radioactive source (humans are always irradiated by BR)

Irradiation = outside body


What does it mean for something to be ‘contaminated’

Unwanted radioactive atoms are on the object. If this radiation enters body, enters living cell, it ionises atoms and the molecules in them, causing tissue damage

Contamination = inside body