Physics P1 and some P2

tanuvmmalode
Flashcards by tanuvmmalode, updated more than 1 year ago
tanuvmmalode
Created by tanuvmmalode over 6 years ago
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Here BBC Bitesize GCSE Physics condensed into a few slides

Resource summary

Question Answer
Kinetic Energy/Movement Energy The energy in moving objects.
Heat Energy/Thermal Energy This energy comes in the form heat.
Light Energy/ Radiant Energy Energy obtained from anything luminous.
Gravitational Potential (GPE) Energy stored in raised objects.
Chemical Energy Stored energy in fuels, foods and batteries.
Sound Energy Energy released by vibrating objects.
Electrical Energy Energy in moving charges or static charges.
Elastic Potential Stored energy in stretched or squashed objects.
Nuclear Stored in the nuclei of atoms.
Internal Energy Contained in thermodynamic (basics of temperature to kinetic theory) systems.
Strain Energy Released when atoms in a molecule rearrange themselves in a chemical reaction.
Energy Transfers Different forms of energy can be transferred from one form of energy to another. e.g. Electrical energy from a switch turns to heat, light and sound energy in a television.
Sankey Diagrams This diagram summarises all the energy transfers taking place. The thicker the line the more energy into that form. Remember you have to draw the diagram to a ratio.
Energy Remember energy can only be transferred usefully, stored or dissipated. It CAN'T be CREATED or DESTROYED
Calculating Efficency The higher the efficiency the more environmentally friendly the item is. Also a device can't be 100% efficient.
Conduction Heat energy can be transferred from one end to another by conduction. Metals in general are better conductors than non-metals which are insulators. Energy always moves from hot end to cold end.
Conduction in metals The electrons in a metal are de-localised (they can move around freely). The atoms are positively charged ions because of the free electrons. The ions being packed together tightly vibrate continually. The hotter the material the more kinetic energy the vibrations have. Kinetic energy is transferred from hot to cold parts of metal because of free electrons. They move through the metal structure colliding with ions as they go giving them MORE kinetic energy.
Convection Heat can be transferred from one place to another.
Convection in fluids and air Liquids and gases are fluids because they flow. The particles in the 'fluids' can move from place to place and because of his particles with MORE heat energy take place of particles with less heat energy. Hot air rises whereas cold air is dense and falls.
Radiation Heat can be transferred by in-fared radiation. In-fared doesn't need particles to transfer heat like convection or conduction instead in-fared is an electromagnetic radiation that involves waves. Without in-fared radiation heat from the sun wouldn't be able to reach the earth.
Surfaces Black materials are better absorbers and emitters of in-fared radiation (remember heat moves from hot to cold so if surrounding is hotter than a black and dull surface it will absorb more radiation than a shiny silver surface). Silver surfaces are poor absorbers and emitters of in-fared.
Reducing Heat Loss 1) Carpets, Curtains and Draught Excluder 2) Double Glazing: no convection or conduction due to vacuum between the two glass panes. 3) Cavity Wall Insulation: Reduces conduction and convection. 4) Loft Insulation: Similar to cavity wall
Clothes Wool is a excellent insulator as it traps lots of air. The more layers we where the more air we trap effectively keeping us warmer for longer.
Work Work done whenever a force moves something. Maybe make an anagram like: Forcing work doesn't make the distance.
GPE m= mass (kg) g= gravitational field (N/kg) h= height (metres) GPE= gravitational potential (joules)
Kinetic Energy KE = ½ × m × v2 KE= kinetic energy (joules) m= mass (kg) v= speed (metres per second)
GPE & KE e.g. A rollercoaster car gains GPE as it travels to the top. Once over the top, the car gains speed as GPE is transferred to KE. As it travels to the top of another loop, KE is transferred to GPE. Note that not all the energy is transferred to or from GPE – some is transferred to the surroundings as heat and sound. All moving objects have KE. The KE an object has depends on its: mass = if the mass doubles, the KE doubles speed = if the speed doubles, the KE increases four times
Power P= power (W/watts) W= work done (joules) t= time (seconds)
Wind Energy Wind is produced as a result of giant convection currents in the Earth's atmosphere, which are driven by heat energy from the Sun. This means that the kinetic energy in wind is a renewable energy resource - as long as the Sun exists, the wind will too. Advantages: 1)Wind is a renewable energy resource and there are no fuel costs. 2)No harmful polluting gases are produced. Disadvantages: 1)Wind farms are noisy and may spoil the view for people living near them. 2)The amount of electricity generated depends on the strength of the wind. 3)If there is no wind, there is no electricity.
Water Energy Advantages: 1)Water power in its various forms is a renewable energy resource and there are no fuel costs. 2)No harmful polluting gases are produced. 3)Tidal barrages and hydroelectric power stations are very reliable and can be easily switched on. Disadvantages: 1)It has been difficult to scale up the designs for wave machines to produce large amounts of electricity. 2)Tidal barrages destroy the habitat of estuary species, including wading birds. 3)Hydroelectricity dams flood farmland and push people from their homes. 4)The rotting vegetation underwater releases methane, which is a greenhouse gas.
Geothermal Energy Advantages: 1)Geothermal energy is a renewable energy resource and there are no fuel costs. 2)No harmful polluting gases are produced. Disadvantages: 1)Most parts of the world do not have suitable areas where geothermal energy can be exploited.
Solar Power Advantages: 1)Solar energy is a renewable energy resource and there are no fuel costs. 2)No harmful polluting gases are produced. Disadvantages: 1)Solar cells are expensive and inefficient, so the cost of their electricity is high. 2)Solar cells do not work at night.
Solar Panels
Fossil Fuels Fossil fuels include coal, oil and natural gas. They were formed from the remains of living organisms millions of years ago and they release heat energy when they are burned. They are non-renewable. They have chemical energy stored within them.
Fossil Fuels ◐.̃◐ Advantages: 1)Relatively cheap and easy to obtain. 2)Much of our infrastructure is designed to run using fossil fuels. Disadvantages: 1)Their supply is limited and they will eventually run out. 2)Coal and oil release sulfur dioxide gas when they burn, which causes breathing problems for living creatures and contributes to acid rain. 3)Fossil fuels release carbon dioxide when they burn, which adds to the greenhouse effect and increases global warming.
Carbon capture Carbon capture and storage is a way to prevent carbon dioxide building up in the atmosphere. It involves separating carbon dioxide from waste gases. The carbon dioxide is then stored underground.
Nuclear power The main nuclear fuels are uranium and plutonium. In a nuclear power station, nuclear fuel undergoes a controlled chain reaction in the reactor to produce heat - nuclear energy is converted to heat energy.
Nuclear Power (◕‿◕✿) Advantages: 1)Do not produce carbon dioxide or sulfur dioxide. 2)Creates more energy than coal being burnt. Disadvantages: 1)non-renewable energy resources. 2)If there is an accident, large amounts of radioactive material could be released into the environment 3)Nuclear waste remains radioactive and is hazardous to health for thousands of years, so it must be stored safely.
Renewable resources {◕ ◡ ◕} Renewable resources of fuel do not cost anything, however the equipment used to generate the power may be expensive to build. Certain resources are reliable, including tidal barrages and hydroelectric power. Others are less reliable, including wind and solar energy.
Average Speed average speed (metres per second) distance (metres) time taken (seconds)
Distance-time graphs A distance-time graph shows how far something travels over a period of time. The vertical axis is the distance travelled from the start. The horizontal axis is the time from the start.
Acceleration
Velocity-time graphs The velocity of an object is its speed in a particular direction. Two cars travelling at the same speed but in opposite directions have different velocities.
Velocity-time graphs calculation The area under the line in a velocity-time graph represents the distance travelled. To find the distance travelled in the graph, you need to find the area of the light-blue triangle and the dark-blue rectangle.
Scalar and vector quantities A quantity that has magnitude but no particular direction is described as scalar. A quantity that has magnitude and acts in a particular direction is described as vector.
Speed Speed is a scalar quantity – it is the rate of change in the distance travelled by an object, while velocity is a vector quantity – it is the speed of an object in a particular direction.
Forces thrust : increases the velocity of an object air resistance : decreases the velocity of an object torque : changes the rotation of an object
Newtons Law F = ma F: unbalanced force m: mass a: acceleration
Friction When two surfaces slide past each other, the interaction between them produces a force of friction. Friction is a force that opposes motion.
Resultant force and Acceleration If the resultant force is zero, a moving object will stay at the same speed. If there is no resultant force then a system is said to be in equilibrium.
Weight or Mass? Mass is a measure of how much matter is in an object. Weight is a force acting on that matter. Mass resists any change in the motion of objects. Weight in newtons whereas mass in kilograms.
Terminal Velocity 1)The object accelerates downwards because of its weight, there is very little air resistance. There is a resultant force acting downwards. The acceleration is constant when the object is close to Earth. 2)As it gains speed, the object's weight stays the same but the air resistance on it increases. There is a resultant force acting downwards. 3)Eventually, the object's weight is balanced by the air resistance. There is no resultant force and the object reaches a steady speed – this is known as the terminal velocity.
Terminal Velocity Graph
Affecting Terminal Velocity The factors affecting the terminal velocity of an object include: 1)mass 2)surface area 3)the acceleration due to gravity
Stopping Distance stopping distance = thinking distance + braking distance
Thinking distance The thinking distance increases if the reaction time increases. This can happen if the driver is: 1)tired 2)distracted 3)under the influence of alcohol or other drugs
Braking distance The braking distance is the distance taken to stop once the brakes are applied. The braking distance increases if: 1)car's brakes or tyres in poor condition 2)poor road & weather conditions 3)car has a larger mass
Thinking distance and Braking distance
Momentum p = m × v p= momentum (kilograms metres per second) m= mass in (kilograms) v= velocity (m/s)
Conservation of momentum As long as no external forces are acting on the objects involved, the total momentum stays the same in explosions and collisions. We say that momentum is conserved.
Forces and Momentums force (newtons) momentum (kilograms metres per second) time (seconds)
Newton’s Third Law Newton’s Third Law of Motion concerns equal and opposite forces. It states that: “If A exerts a force on B, then B exerts an equal but opposite force on A”.
Car safety features When there is a car crash, the car, its contents and the passengers decelerate rapidly. They experience great forces because of the change in momentum which can cause injuries.
Seat belts Seat belts stop you tumbling around inside the car if there is a collision. They are designed to stretch a bit in a collision. This increases the time taken for the body's momentum to reach zero, and so reduces the forces on it.
Air bags Air bags increase the time taken for the head's momentum to reach zero, and so reduce the forces on it. They also act a soft cushion and prevent cuts.
Crumple zone Crumple zones are areas of a vehicle that are designed to crush in a controlled way in a collision. They increase the time taken to change the momentum of the driver and passengers in a crash, which reduces the force involved.
Charge and current Electric current is the rate of flow of electric charge. No current can flow if the circuit is broken. An electric current flows when electrons move through a conductor. Electricity passes through metallic conductors as a flow of negatively charged electrons are free to move from one atom to another.
Calculating Current current in amperes (amps or A) charge in coulombs (C) time in seconds
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