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Descrição
FlashCards por Natalia Cliff, atualizado more than 1 year ago
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Criado por Natalia Cliff
mais de 7 anos atrás
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| Questão | Responda |
| What is Newton's third law? | Whenever two objects interact, the forces they exert on each other are equal and opposite |
| What is a resultant force? | A number of forces acting at a point may be replaced by a single force that has the same effect on the motion as the original forces all acting together. This single force is calle dteh resultant force |
| What effect does a resultant force have? | A resultant force acting on an object may cause a change in its state of rest or motion |
| Resultant Forces on Stationary Objects | -If the resultant force is zero the object will remain stationary -If the resultant force isn't zero the object will accelerate in the direction of the resultant force |
| Resultant Forces on a Moving Object | -If the resultant force is zero the object will continue moving at the same speed in the same direction -If the resultant force isn't zero the object will accelerate in the direction of the resultant force |
| Equation for Acceleration of an Object | F=ma |
| Distance Time Graph | |
| How can you find the speed of an object from a distance time graph | Gradient of a distance time graph is the speed |
| Velocity Time Graph | |
| How can you calculate distance travelled and acceleration from a Velicity Time Graph? | -Gradient is the accelaration -Distance travelled is the area under the graph |
| Equation for accelaration | a=(v-u)/t |
| What are the forces acting on a vehicle travelling at a steady speed? | The resistive forces (mainly air resistance) balance out the driving forces |
| Factors affecting the Braking Force | -The greater the speed of th vehicle, the greater the braking force needed to stop it in a certain distance |
| Factors affecting stopping distance | Thinking distance (distance the vehicle travels whilst the driver thinks) -Tiredness -Drugs -Alcohol -Distractions Braking distance (distance the vehicle travels under the breaking force) -Bad road conditions (icy roads) -Bad weather conditions (rain) -Bad vehicle condition (breaks and tires) - |
| How do Brakes work? | When the brakes of a vehicle are applied, work done between the brakes and the wheel reduces the kinetic energy of the vehicle so the temperature of the brakes increase |
| Friction on a Falling Object | The faster an object moves through a fluid the greater the frictional force that acts on it |
| Terminal Velocity | -An object falling through a fluid will initially accelerate due to the force of gravity -Eventually the resultant force will reach zero as the increased air resistance balances out the force of the weight of the object -The object is then moving at terminal velocity as it cannot accelerate any more |
| Velocity Time Graph for Terminal Velocity | |
| Changing the Shape of an Object | A force acting on an object may cause a change in the shape of the object |
| Storing Elastic Potential Energy | A force applied to an elastic object such as a spring will result in the object streching and storing elastic potential energy |
| Hooke's Law Graph and Equation |
F=ke
Image:
Hooke's Law (image/gif)
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| What is work done? | -When a force causes an object to move through a distance work is done W=Fd -Energy is transferred when work is done |
| What is Power? | -Power is the work done or energy transferred in a given time E=P/t |
| What is Gravitational Potential Energy? | Gravitational Potential Energy is the energy that an object has by virtue of its position in a gravitational field E=mgh |
| What does Kinetic Energy depend on? | The kinetic energy of an object depends on its mass and speed E=(mv^2)/2 |
| What is Momentum? | Momentum is a property of moving object P=mv |
| What is the Conservation of Momentum? | In a closed system the total momentum before an event is equal to the total momentum after the event |
| How do Objects gain Static Electricity? | -When two insulating materials rub against each other they become electrically charged -Negatively charged electrons are rubbed from off one material onto another -The material that gains electrons becomes negatively charged -The material that loses electrons becomes positively charged |
| How do two Electrically Charged Objects react to each other? | -When two electrically charged objects are brought together they exert a force on each other -Two objects with the same type of charge repel each other -Two objects that carry different types of charges attract each other |
| What is Electrical Current? | Electric current is a flow of electric charge. The size of the electric current is the rate of flow of electric charge I=Q/t Q is Charge in Coulombs |
| What is Potential Difference (Voltage)? | The potential difference between two points points in an electric circuit is the energy transferred per coulomb of charge that passes between the points V=W/Q W is work done in Joules |
| Circuit symbols |
Image:
Circuit Symbols (image/jpeg)
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| Thermistors | -A temperature dependant resistor -In hot conditions resistance drops -In cool conditions resistance goes up -Make useful temperature detectors |
| Light-Dependant Resistor (LDR) | -LDR is a resistor that's dependant on light -In bright light resistance falls -In darkness resistance is high -Used in automatic night lights and Burglar alarms |
| Current-Potential Difference Graphs | -Are used to show how the current through a component varies with the potential difference across it |
| Current-Potential Difference Graph for a resistor with a constant temperature | |
| How can you calculate resistance? | -Can be found by measuring the current through and voltage across a component -The current through a resistor (at a constant temperature) is directly proportional to the voltage across it V=IR |
| Components Connected in Series | -The total resistance is the sum of the resistance of each component -The same current through all components -The total potential difference of the supply is shared between the components |
| Components Connected in Parallel | -The potential difference across all components is the same -The total current through the whole circuit is the sum of the currents through the separate components |
| Resistance in a Filament Bulb | -The resistance of a filament bulb increases as the temperature of the filament increases -When an electrical charge flows through a resistor, the resistor gets hot |
| Current Through a Diode | |
| LED Lighting | -An LED emits light when current flows through it in a forward direction -Becoming more common in lighting as they use a much smaller current than other forms of lighting |
| AC and DC Electricity | -Batteries supply current that always passes in the same direction, called DC -Mains Electricity in an ALternating Current (AC) with a frequency of 50 Hz and 230 V in the UK |
| Finding Frequency | T=1/f f= \(\lambda\) / v |
| Structure of a 3 Pin Plug |
Structure of a cable is very similar, same 3 wires that are all separately insulated and then have one outer insulating cover
Image:
Plug (image/gif)
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| Dealing with Electrical Faults | -If an electrical fault causes too great a current, the circuit is disconnected by a fuse or circuit breaker in the live wire -When the current in a fuse exceeds the rating of the fuse it will melt -The thicker the cable the higher the fuse value -Some circuits are protected by Residual Current Circuit Breakers (RCCBs) -RCCBs work by detecting a difference in the current of neutral and live wires -Appliances with metal casings are usually earthed -Some appliances, however, are double insulated and so don't need to be earthed -The earth wire and fuse both protect the wiring of the circuit |
| What is Power? | The rate of energy transfer P=E/t P=IV |
| How are Energy, Potential Difference and Charge related? | E=VQ |
| Rutherford and Marsden Experiment | -Early model of the atom said that it was a positive sphere with negative electrons in it, like plums in a plum pudding -Fired a beam of alpha particles at a thin gold foil -Expected them to pass through, but some came out at an angle or came straight back -Realised they were being repelled and deflected by a concentrated centre of positive charge |
| Atomic Structure | If you really don't know what protons, neutrons, electrons, isotopes and ions are check out the C1 flashcards |
| What are Radioactive Substances? | Substances that give out radiation from the nuclei of their atoms all the time, whatever is done with them |
| Where does Background Radiation come from? | -Rocks -Cosmic rays from space -Fallout from nuclear weapons tests -Fallout from nuclear accidents |
| What is Radiation made of? | -Alpha particles are two protons and two neutrons -Beta particles are one electron -Gamma radiation is electromagnetic radiation |
| Alpha and Beta Decay | -When alpha particles are emitted the nucleus loses two protons and two neutrons -When a particle emits beta radiation a neutron in the nucleus turns into a proton |
| Properties of Alpha particles | -Highly ionising -Cannot travel far in air (eventually ionises atoms in the air) -Not very penetrating (can be stopped by a hand) |
| Properties of Beta Particles | -Moderately ionising -Can travel moderately far in water -Can be stopped by a few mm of aluminium |
| Properties of Gamma Particles | -Not very ionising -Can travel furthest through air -Most penetrating, can be stopped by a few cm of lead |
| Radiation in Electric and Magnetic Fields | -Alpha and Beta particles are both deflected in opposite directions -Beta deflected more, as despite having half the charge of Alpha it has a much smaller mass -Gamma radiation not affected as it has no charge |
| Use and Dangers of Radiation | -Alpha Radiation used in smoke detectors, highly ionising but on the ceiling so far away from people -Beta radiation used as medical tracers, as it is less ionising than Alpha -Beta radiation also used in monitoring the thickness of materials -Gamma radiation is used to sterilise medical equipment and treat cancer |
| Half Life | -The Half Life of a radioactive isotope is the average time it takes for the count rate from a sample containing from a sample containing a radioactive isotope falls to half it's initial level -Or the time it takes for the number of radioactive nuclei of the isotope in a sample to halve |
| What are the two fissionable substances used in nuclear reactors? | -Uranium-235 -Plutonium-239 |
| Process of Fission | -For fission to occur, the nuclei must first absorb a neutron -The nucleus then splits into two smaller nuclei and 2 or 3 neutrons, energy is also released -The neutrons may then go on to produce chain reactions -That's why control rods made of Boron can be lowered to absorb these extra neutrons |
| Nuclear fusion | -The joining of two atomic nuclei to form a larger on -Stars use this to release energy -Fusion in stars produces all the naturally occurring elements -These elements are distributed throughout the universe by an exploding supernova at the end of it's life cycle |
| Life Cycle of a Star | -Stars form when enough dust and gas from space is pulled together by gravitational attraction (smaller masses can also be attracted and form planets) -During the main sequence period of it's life-cycle a star is stable because the forces are balanced - |
| Life Cycle of a Star |
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