Karteikarten
Physics - Additional
Karten in diesem Stapel (158)
- 1What is the speed?How fast you're going
- 2What is the velocity?How fast you're going in a certain direction
- 3What are the units for speed and velocity?m/s or mph
- 4How do you calculate the speed?Speed = distance / time
- 5What does the gradient show on a distance-time graph?The speed
- 6What do straight or uphill sections mean on a distance-time graph?It's travelling at a steady speed
- 7What do downhill sections mean on a distance-time graph?It's going back towards the start
- 8What do curves represent on a distance-time graph?Acceleration or deceleration
- 9What is the acceleration?How quickly the velocity is changing
- 10How do you calculate the acceleration and what are the units?change in velocity / time taken
m/s^2 - 11What is the gravitational field strength on Earth?10N/kg
- 12What are the units for weight?N
- 13How do you calculate the weight?Weight = mass x gravitational field strength
- 14What does the gradient represent on a velocity-time graph?Acceleration
- 15What do uphill sections represent on a velocity-time graph?Acceleration
- 16What do downhill sections represent on a velocity-time graph?Deceleration
- 17What is the area under a velocity-time graph equivalent to?Distance travelled
- 18What does a curve represent on a velocity-time graph?Change in acceleration
- 19What is the resultant force?The overall force on a point or object
- 20What happens to the object if the resultant force is 0?Will be stationary; no change in velocity
- 21What will happen to the object if there is a non-zero resultant force?It will accelerate in the direction of the force
- 22What will happen to an object if there is zero resultant force?It will maintain a steady speed
- 23Formula for calculating the resultant force?F = m x a
F - resultant force in N
m - mass in kg
a - acceleration in m/s^2 - 24What happens to the forces exerted when 2 objects interact?They are equal and opposite
- 25What does friction do?Slow objects down
- 26What direction does friction act in?The opposite direction to the movement
- 27What is friction also known as when an object passes through a fluid?Drag
- 28How can you reduce the drag?Keep the objects shape streamlined
- 29What happens to the drag when the speed increases?The drag increases, so the object has to work harder to maintain a steady speed
- 30What is terminal velocity?When the frictional force is equal to the velocity
- 31What 2 factors affect the terminal velocity of falling objects?Shape and area
- 32What does a wider shape/area result in?More air resistance.
- 33What 2 factors affect your stopping distance?•Thinking distance
•Braking distance - 34What is the thinking distance?The distance the vehicle travels during the drivers reaction time
- 352 main factors that affect the thinking distance?•How fast you're going
•How dopey you are - drugs/alcohol/tiredness - 36What is the braking distance?The distance the car travels under the braking force
- 37What 4 main factors affect the braking distance?•How fast you're going - faster = further
•How good the brakes are - rusty = bad
•How good the tyres are - car can skid
•How good the grip is - weather/road conditions - 38What is 'work done' the same as?Energy transfer
- 39How do you calculate the work done?W = F x d
W - Work done (J)
F - Force (N)
d - distance (m) - 40What is gravitational potential energy?The energy an object has because of its height.
- 41How do you calculate the gravitational potential energy?Ep = m x g x h
Ep = gravitational potential energy (J)
m = mass (kg)
g = gravitational field strength
h = height (M) - 42What is kinetic energy?Energy of movement
- 43How do you calculate kinetic energy?Ek = 1/2 x m x v^2
Ek = kinetic energy (J)
m = mass (kg)
v = speed (m/s) - 44What is the kinetic energy formula equal to?Work done formula
- 45What happens to the Ep and Ek when an object falls?Ep is converted into Ek
Kinetic energy gained = potential energy lost - 46What do elastic objects store energy as?Elastic potential energy
- 47What is the extension of an elastic object equal to?The force or load applied
- 48How do you calculate the force applied to an elastic object?F = k x e
F = force (N)
k = spring constant (N/m)
e = extension (m) - 49What is the limit of proportionality?The maximum force that the elastic object can take - shown on a graph where force and extension are no longer proportional
- 50What is power?The rate of doing work
- 51How do you calculate power?P = E/t
P = Power (W)
E = Work done or energy transferred (J)
t = time taken (s) - 522 ways to calculate the power output of a person?•Timed run
•Timed acceleration - 53How do you calculate the momentum?p = m x v
p = momentum (kg m/s)
m = mass (kg)
v = velocity (m/s) - 54What is the momentum before equal to?The momentum after
- 55What happens to the momentum when a force acts on an object?Momentum changes
- 564 examples how cars are designed to convert kinetic energy safely in a crash?•Crumple zones at the front and back of the car crumple on impact - increase impact time
•Seat belts stretch slightly - increase time taken for wearer to stop, reduces force on chest
•Side impact bars in car door panels - direct kinetic energy of crash away from passengers
•Air bags - slow you down more gradually - 57What do regenerative brakes do and how?•They use the system that drives the vehicle to do the majority of the braking by putting the motor into reverse
•Motor acts as an electric generator at the same time - converts kinetic energy into electric energy which is stored as chemical energy in vehicles battery - 58When do cars reach their top speed?When the resistive force equals the driving force provided by the engine
- 59Why do aerodynamic cars reach higher speeds?•Air flows easily around them and so they have a lower air resistance
•Car has less air resistance to overcome so the forces balance quicker - 60What is a build up of static electricity caused by?Friction
- 61Which type of charge moves?The negative charge (electrons)
- 62What are conductors?Materials in which electrical charges move easily
- 63What is the current and what is it measured in?•Flow of electric charge round the circuit
•Unit = Amps, A - 64What is the potential difference and what is it measured in?•Driving force which pushes the current round
•Unit = Volts, V - 65What is the resistance and what is it measured in?•Anything in the circuit which slows the flow down
•Unit = Ohms, Ω - 66Formula for calculating the current?I = Q/t
I = current (A)
Q = charge (C)
t = time (s) - 67Formula for calculating the potential difference (voltage)?V = W/Q
V = Potential difference or voltage (V)
W = work done (J)
Q = charge (C) - 68What does the ammeter do?•Measures the current in amps
•Must be placed in series - 69What does the voltmeter do?•Measure the potential difference in volts
•Must be placed in parallel around the component - 70What does the graph for different resistors look like?Current is directly proportional to P.D
- 71What does the graph for a filament lamp look like?As the temperature of the filament increases, the resistance increases
- 72What does the graph for a diode look like?Current will only flow through a diode in one direction. The diode has a high resistance in the opposite direction
- 73How do you calculate the potential difference?V = I x R
V = potential difference (V)
I = Current (A)
R = Resistance (Ohms) - 74What is a diode used for?To regulate the potential difference in circuits - current flows freely in one direction but not in other
- 75What are light-emitting diodes?An LED emits light when a current flows through it in the forward direction
- 76Why are LED's more useful than normal diodes?•Use a smaller current
•Used in appliances to indicate they're on - 77What is a light-dependent resistor (LDR)?Resistor that is dependent on the intensity of light
- 78When is the resistance highest in an LDR?In darkness
- 793 uses of LDR's?•Automatic night lights
•Outdoor lighting
•Burglar detectors - 803 uses of LED's?•Digital clocks
•Traffic lights
•Remote controls - 81What is a thermistor?A temperature dependent resistor
- 82What happens to the resistance in a thermistor in hot conditions?Resistance drops
- 832 uses for thermistors?•Car engine temperature sensors
•Electronic thermostats - 84What is a series circuit?•All components are connected in a line, end to end, between the positive and negative of the power supply
•Circuit wont work if one thing has been disconnected - 85What happens to the potential difference in a series circuit?•It is shared between the components
•Voltages round the circuit add up to equal the source voltage (V = v1 +v2) - 86What happens to the current in a series circuit?•Same current flows through all parts
•a1 = a2 - 87What happens to the resistance in a series circuit?•Total resistance is the sum of all the resistances
•R = r1 + r2 + r3 - 88What is a parallel circuit?•Each component is separately connected to the positive and negative of the power supply
•If you remove or disconnect something, it will hardly affect the rest - 89What happens to the potential difference in parallel circuits?•Potential difference is the same across all components
•v1 = v2 = v3 - 90What happens to the current in parallel circuits?•Shared - total current is equal to total of all the currents through the separate components
•A = a1 + a2 - 912 advantages of parallel circuits?•Everything can be turned on and off separately
•Everything always gets the full voltage from the battery - 92What voltage is the UK mains supply and what current does it use?230 V
Alternating current - 93What supply uses a direct current?Battery supply
- 94What happens when you plug an AC supply into an oscilloscope?Goes up and down - sometimes positive and sometimes negative
- 95What happens when you plug a DC supply into an oscilloscope?Get a straight vertical line as the voltage is the same
- 96How do you calculate the frequency for an AC supply?Frequency (Hz) = 1 / time period (s)
- 979 hazards in the house?•Long cables
•Frayed cables
•Cables in contact with something hot/wet
•Water near sockets
•Shoving things into sockets
•Damaged plugs
•Too many plugs in one socket
•Lighting sockets without bulbs in
•Appliances without their cover on - 98What are the 3 wires in cables, what colour are they and what do they do?•Brown live wire - alternates between high +ve and -ve voltage
•Blue neutral wire - always at 0v
•Green/yellow earth wire - protecting wiring and works with fuse to prevent fire and shocks - 994 safety features of the wiring inside a plug?•Right coloured wire is connected to each pin and firmly screwed in
•No bare wires are showing inside plug
•Cable grip tightly fastened over the cable outer layer
•Thicker cables have less resistance so they carry more current - 1002 safety features of the plug?•Metal parts are made of copper/brass as they are good conductors
•Case/cable grip/insulation made of rubber/plastic because they're good insulators and flexible - 101What does earthing mean?Case must be attached to an earth wire
- 102How do earthing and fuses prevent electrical overloads?•If fault develops and live wire touches case, a big current flows through the live wire, into the case and down the earth wire because the case is earthed
•Surge in the current melts the fuse which cuts off the live supply and breaks the circuit - 103What are two-core cables?Cables that only carry the live and neutral wires because they are double insulated
- 104What is a circuit breaker?•An electrical safety device similar to fuses - they protect the circuit from damage if too much current flows
•Break the circuit by opening a switch - 1053 advantages of circuit breakers compared to fuses?•Can be easily reset - fuses have to be replaced
•Faster than fuses
•Works for small current changes - 1061 disadvantage of current breakers to fuses?More expensive
- 107When is an appliance more efficient?When it wastes less energy
- 108How do you calculate the energy transferred by an appliance in a given time?E = P x t
E = Energy transferred (kJ)
P = Power rating (kW)
t = time (mins) - 109How do you calculate the electrical power?P = I x V
P = Power (W)
I = Current (V)
V = Potential difference (A) - 110How do you calculate the energy transformed?E = Q x V
E = Energy transformed (J)
Q = Charge (C)
V = Potential difference (A) - 111What did Rutherford and Marsdon realise?•Most of the mass of the atom was concentrated at the centre in the nucleus
•Nucleus has a large positive charge
•Most of the atom is just empty space - 112Relative mass and charge of a proton?•Mass = 1
•Charge = +1 - 113Relative mass and charge of a neutron?•Mass = 1
•Charge = 0 - 114Relative mass and charge of an electron?•Mass = 1/2000
•Charge = -1 - 115What are isotopes?Atoms with the same number of protons and electrons but a different number of neutrons
- 116What is background radiation?Radiation that is present at all times all around us
- 117What are the relative proportions of background radiation?•51% radon gas
•14% rocks and building materials
•12% food
•12% medical x-rays
•10% cosmic rays
•!% from the nuclear industry - 118What are alpha particles and why?Helium nuclei - they have 2 protons and 2 neutrons (4, 2)
- 119What is the size of alpha particles and how fast/slow do they move?•Relatively big and heavy
•Slow moving - 120How far do alpha particles penetrate materials and why?Not very far because they are stopped quickly even when travelling through air due to their heaviness and large size
- 121Are alpha particles strongly ionising or weakly ionising?They are strongly ionising because they are large (strongly ionising = bash into atoms and knock lots of electrons off them before they slow down which creates lots of ions)
- 122What are beta particles?A beta particle is an electron (0, -1)
- 123What is the size of beta particles and how fast/slow do they move?•Quite small
•Move quite fast - 124How far do beta particles penetrate materials?They penetrate moderately into materials before colliding and also have a long range in air
- 125Are beta particles strongly ionising or weakly ionising?Moderately ionising
- 126What happens for every beta particle emitted?A neutron turns to a proton in the nucleus
- 127What are gamma rays?Very short wavelength EM waves
- 128How far do gamma rays penetrate materials?Far into materials without being stopped and pass straight through air
- 129Are gamma rays strongly ionising or weakly ionising and why?Weakly ionising because they tend to pass through something rather than collide with atoms - eventually they hit something and do damage
- 130How do you balance alpha decay equations?Take away 4 from the top number (of the product) and 2 from the bottom and add 4, 2 He
- 131How do you balance beta decay equations?Leave the top number the same and add one number to the bottom number, and add 0, -1 e
- 132How are alpha and beta particles deflected?By electric and magnetic fields
- 133What charge do alpha and beta particles have?Alpha - positive
Beta - negative - 134What happens when alpha and beta particles are deflected?•Deflected in opposite directions because of their opposite charges
•Alpha particles have a larger charge and feel a greater force in fields, but they're deflected less because they have a greater mass - 135Why doesn't gamma radiation get deflected by electric or magnetic fields?Because it is an EM wave and has no charge
- 136What does the damage caused by radiation depend on?The radiation dose
- 137What does radiation dose depend on?•Location and occupation
•Certain underground rocks/miners/nuclear industry workers/radiographers/planes - 138Definition of half-life?Half-life is the average time it takes for the number of nuclei in a radioactive isotope sample to halve.
- 139How do you find the half-life?Keep halving the initial count until it reaches the other number given in the exam question
- 140What kind of radiation do smoke detectors use?•Alpha radiation - a weak source of alpha radiation is placed next to 2 electrodes which causes ionisation and a current flows between them.
•If there is a fire the smoke absorbs the radiation, so the current stops and the alarm sounds - 141What kind of radiation do tracers in medicine use?•Beta or gamma
•Injected/swallowed into people and their progress around the body is followed by an external director
•Used as they have a short half-life - 142What kind of radiation does radiotherapy use?Gamma rays - kill cells
- 143What kind of radiation does sterilization of food/surgical instruments use?Gamma rays - kills microbes, keeping food fresh for longer
- 144Why is radiation dangerous?It can cause cells to mutate
- 145When are beta and gamma sources most dangerous and why?•Outside the body
•Can get inside to the delicate organs, whereas alpha is less dangerous because it can't penetrate the skin - 146When are alpha sources most dangerous and why?•Inside the body
•Alpha sources do all their damage in a very localised area. Beta and gamma are less dangerous inside the body because they mostly pass straight out without doing much damage - 1474 safety precautions when handling radioactive materials?•Use radioactive sources for as short a time as possible - so exposure is minimal
•Always use tongs - no skin contact
•Hold the source at arms length - decreases radiation that hits you
•Keep source pointing away from body and avoid looking directly at it - 1483 ways how we use lead to protect us from exposure to radiation?•Store radioactive sources in a lead box when the experiment is over
•Medical professionals wear a lead apron and stand behind lead screens
•The areas of the patients' body that isn't being treated is protected with lead - 149What is nuclear fission?The splitting up of big atomic nuclei
- 150How do nuclear power stations use nuclear fission?Water -> steam -> turbine -> generator -> electricity
•When atomic nuclei split up they release energy in the form of heat - 151What happens in nuclear fission?•Slow moving neutron is absorbed into uranium or plutonium nucleus. Becomes unstable and splits
•Each time it splits up, it spits out 2 or 3 neutrons, which may hit another nucleus, causing a chain reaction - 1523 problems with nuclear power?•Disposal of waste - difficult and expensive to dispose of safely
•Fuel is cheap but overall cost of power is high due to cost of power plant and decommissioning - takes decades
•Nuclear power carries the risk of radiation leaks (like Chernobyl) - 153What is nuclear fusion and what does it release?•The joining of small atomic nuclei
•Releases a lot of energy (more than fission) - all the energy released in stars is from fusion - 154An advantage of nuclear fusion?Doesn't leave behind a lot of radioactive waste
- 155A disadvantage of nuclear fusion?Fusion can only happen at really high temperatures and you can't hold hydrogen at temperatures that high
- 156Describe how a main sequence star is formed?•Nebula - gravitational forces pull dust and gas together
•Protostar - gravitational energy becomes heat energy and temperature increases. Nuclear fusion takes place
•Main sequence star - long stable period where heat from fusion provides an outward pressure to balance gravitational forces pulling everything inwards - 157Describe how a main sequence star becomes a red supergiant and what happens to it?•Hydrogen begins to run out so star begins to die
•Becomes red due to heat
•Collapses due to gravity and explodes into a supernova - elements heavier than iron are formed
•Cools down and becomes a neutron star, and it may become a black hole if it is big enough - 158Describe how a main sequence star becomes a red giant and what happens to it?•Hydrogen begins to run out so star begins to die
•Becomes unstable and ejets its outer layer of dust and gas as a planetary nebula
•Becomes a white dwarf as it's very hot
•Then becomes a black dwarf when it cools down
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- Karteikarten am Physics - Additional, erstellt von absaroke am 17/06/2016.
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