Science - physics
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Science - physics - Leaderboard
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| 🇬🇧 | 🇬🇧 |
| What are the nine energy stores? | The nine energy stores are LSG Cenek, or Light, Sound, Gravitational potential energy, Chemical, Electrical, Nuclear, Elastic potential energy, and Kinetic |
| What is the equation to calculate voltage? | The equation to calculate voltage: Voltage = current x resistance V = I x R |
| What’s the equation to calculate the charge? | The equation to calculate the charge: Charge = current x time Q = I x t |
| What is kinetic energy? | Kinetic energy is the energy stored in moving objects, and therefore stationary objects don’t have kinetic energy |
| What's the equation for kinetic energy? | Ek (J) = 0.5 x mass(kg) x velcoity^2 (m/s) |
| What is elastic potential energy? | Elastic potential energy is energy stored as a result of applying a force to stretch an elastic object |
| How can the kinetic energy of a moving object be increased? | The kinetic energy of a moving object can be increased by doubling the speed of the object, which quadruples the kinetic energy, and the kinetic energy of a stationary object can be increased by doubling the mass which doubles the kinetic energy. |
| What is the equation to calculate the energy transferred? | The equation to calculate the energy transferred: Energy transferred= charge x current x resistance E = Q x I x R |
| What is extension in a spring? | Extension in a spring is when it stretches from an applied force. |
| What is the equation to calculate power? | The equation to calculate power: Power = current x voltage P = I x V |
| How can the elastic potential energy stored in a spring be increased? | The elastic potential energy stored in the spring can be increased by the force stretching or compressing the spring which does work on the spring. |
| What is the second equation to calculate power? | The second equation to calculate power: Power = current^2 x resistance P = I^2 x R |
| When is the extension is directly proportional to the force? | The extension is directly proportional to the force when the straight line of the extension against the force applied graph goes through zero. However, if a greater force is applied, the extension will no longer be directly proportional to the force because the spring has been stretched beyond its limit of proportionality so it won’t be able to return to its original length if the force is removed |
| What is the equation to calculate energy? | The equation to calculate energy: Energy = charge x voltage E = Q x V |
| What's the equation for elastic potential energy? | Ee = 0.5 x k x e^2 elastic potential energy (J) = 0.5 x spring constant measured (nm) x extension (m) |
| What is the second equation to calculate energy transferred? | The second equation to calculate energy transferred: Energy transferred: current x time x voltage E = I x t x V |
| What is gravitational potential energy? | Gravitational potential energy is the energy stored in an object due to its position above the Earth’s surface, which is due to the force of gravity acting on the object |
| What is the equation for Gravitational potential energy? | Ep = m x g x h Gravitational potential (J) = mass (kg) x gravitational field strength (n/kg) x height (m) |
| What is specific heat capacity? | The Specific heat capacity of a substances is the amount of energy required to raise the temperate of 1kg of the substance by 1 degree celsius |
| What is the specific heat energy equation? | E = m x c x 0 (theta) Change in thermal energy (J) = mass (kg) x specific heat capacity (J/Kg degree Celsius) x temperate change (degree celsius) |
| What is an energy system? | An energy system is an object or group of objects, and closed energy systems cannot lose matter or energy |
| What is the principle of conservation of energy? | The principle of conservation of energy is energy can only be transferred to another form of energy or dissipated to the surroundings, it cannot be created or destroyed |
| What are the energy transfers that take place in a pendulum? | At the top of the pendulum, the mass has the maximum store of gravitational potential energy and as the pendulum swings this is transferred to the kinetic energy store, and at the bottom of the swing, the mass as has maximum kinetic energy store since that’s where it’s moving at the fastest speed. As the mass swings back up the kinetic energy store transfers to the gravitational potential energy store again. |
| What is problem with the energy transfer pendulum model? | The problem with the energy transfer pendulum model is that friction hasn’t been considered. Friction happens as the pendulum passes through the air particles and it causes energy to be transferred to thermal energy stores. The fixed point and the air around the pendulum gradually get warmer and these stores of thermal energy are not useful because energy is being dissipated (wasted) – which will cause the pendulum to gradually swing will less energy and eventually stop |
| How can unwanted energy transferred be reduced? | Unwanted energy transfers can be reduced by reducing friction, which can be done by using a lubricant such as oil on the fixed point, or by removing the air particles from around the pendulum |
| What is the equation for work done? | Work done (J) = Force (N) x Distance (m) |
| Describe the energy transfers that take place during bungee jumping | At the start of the jump all the energy in the system is stored as gravitational potential energy when the jumper falls the gravitational potential energy is transferred to kinetic energy when the bungee rope starts to tighten the kinetic energy store is at its maximum and when the ropes fully extended the kinetic energy becomes zero because the jumper isn’t moving – at which point all the energy has been transferred to the elastic potential energy store. Now the bungee rope recoils and energy is transferred from the elastic potential energy store back to the kinetic energy store and during the ascent the energy transfers from the kinetic energy store back to the gravitational potential energy store. Finally, at the top of the ascent, all the energy is in the gravitational potential energy store. |
| Why does the jumper never return back to the original position in bungee jumping | The jumper never returns back to the original position because energy is dissipated as thermal energy due to friction with air particles and also due to the stretching effects in the bungee rope which isn’t fully elastic so some thermal energy is always dissipated during stretching and recoil |
| What is work? | Work is the energy transferred to or from an object when an application of force is placed along a displacement |
| How much work needs to be done to bring an object back to the earth’s surface? | When an object is thrown work is done against the force of gravity, so it gains gravitational potential energy, and it will need the same amount of work done would have to be exerted by the force of gravity to bring it back to the earth’s surface. |
| What is power? | Power is the rate at which energy is transferred or work is done |
| What are the equations for power? | Power (Watts) = energy (J)/time (s) but the equation for electrical power is Power (W) = Current (A) x Voltage (V) |
| What are the efficiency equations? | Efficiency = useful output energy transfer/ total input energy transfer Efficiency = useful power output / total power input |
| How do you know if you have incorrectly calculated efficiency and how can the efficiency be calculated as a percentage? | Keep in mind that any answer above 1 which is virtually impossible for this equation and therefore if you do have a value above 1 as your answer, you have most likely divided the input by the output instead of the output by the input. And changing the original decimal answer into a percentage is done by multiplying the decimal by 100 |
| What are the issues with heating water in a pan, and how can they be solved? | When water is heated in a pan thermal energy can be lost as it can pass into the air at the water’s surface and around the edges of the hob, thermal energy can be more directly passed from the hob into the water by using a pan with a wider base and a lid. Secondly, when water is heated in a pan, thermal energy can be used to heat the base of the pan alone. To prevent this the heating element can be placed inside the water, which is how an electrical kettle works |
| What are the advantages of heating water in a kettle? | The advantage of heating water in a kettle is less thermal energy passes from the walls and the lid of the kettle, into the air. This is because kettles are made of plastic; a less successful heat conductor than metal; making water have lower thermal conductivity, therefore kettles are more efficient for heating water than pans which are usually made from metal; an efficient heat conductor, that enables heat to pass through the pan's sides and lid, and into the air. |
| What is the effect of thermal conductivity on energy? | The higher the thermal conductivity of a materials the higher the rate of energy transfer by conduction across that material. |
| What is the thermal conductivity of modern houses in terms of brickwork, and how can is it tackled? | Modern houses are built from two layers: an external brick wall and an internal breezeblock wall, between the walls, is a cavity and the thermal conductivity of walls built like this is fairly high therefore a lot of thermal energy can transfer out the house. To tackle this issue, builders pack the cavity with an insulating material that has a very low thermal conductivity, which reduces the overall thermal conductivity escaping the house |
| What is the thermal conductivity of modern houses in terms of glass work, and how can is it tackled? | In houses thermal energy can escape from the windows. Single glazed windows have high thermal conductivity, so most house have double glazed windows, which have a lower thermal conductivity so less thermal energy can exit the house |
| What is the specific heat capacity for copper, aluminium, and gold? | The specific heat capacity for copper is 385J/Kg degrees C, for aluminium it is 913 J/Kg degrees C, and for Gold, it is 126J/kg degrees C. |
| What do you do before the specific heat capacity practical? | Before the specific heat capacity practical, put a heater in the aluminium block and in the smaller hole put a thermometer and a few drops of water to ensure accurate readings. |
| How is the specific heat capacity practical done? | In the specific heat capacity practical take a reading of the initial temperature, then turn the power supply and stop-clock at the same time. Now find the power by counting the number of flashes on a joule meter per second and multiplying that by 100, although because this power can get lost when it goes into the heater the power can also be measured with a voltmeter. To do this put an ammeter in series with the component and put a voltmeter around the component, then multiply the readings of voltage and current = power Now draw a graph of the time in seconds on the x-axis against the temperature in degrees Celsius on the y axis Then find the specific heat capacity using the equation SHC = power/mass x time/temperature change Finally, repeat the practical using the copper and gold block to see how their SHCs compare. |
| How can thermal heat being lost through the roof be reduced? | A lot of thermal energy can escape from the roof of a house, this can be reduced with loft insulation, which has a low thermal conductivity, reducing the rate at which thermal energy passes through |
| How can the time and temperature change be calculated from the graph? | From the graph, the time and temperature change can be calculated by drawing a 90-degree triangle to measure both values |
| Why may the SCH of a practical be higher than aluminium’s SCH? | The SCH of a practical may be higher than aluminium’s SCH because the aluminium block is not insulated so energy is lost to the surroundings. This may be solved by insulating the block using foam on the sides and bottom. |
| What is the difference between a histogram and a bar chart? | A bar chart is used to display categorical data whereas a histogram displays numerical data therefore they are no spaces between the bars in histograms |
| How do you convert minutes into seconds and hours into seconds? | To convert minutes into seconds multiply the number of minutes by 60, and to convert hours into seconds multiply the number of hours by 3600 |
| Describe the specific heat capacity practical of oil | Begin by placing a beaker on a balance, now add the oil to the breaker and record its mass, place a thermometer and an immersion heater into the oil. Read the starting temperature of the oil and warp the breaker in insulating foam to reduce thermal energy transfer to the surroundings. Connect a joule meter and a power pack to the immersion heater and the joule meter states how many joules of electrical energy passes into the immersion heater. Leave the set up for 30 minutes to allow the temperature to rise to a high enough level to ensure accurate thermometer readings. Read the number of joules of energy that passed into the immersion heater and read the final temperature of the oil. |
| Why may the specific heat capacity practical using oil and a beaker be inaccurate? | The specific heat capacity practical may be inaccurate because thermal energy is passing out of the beaker into the air, this problem can be reduced by using an insulator with a lower thermal conductivity Secondly, not all the thermal energy passes into the oil, this can be reduced by ensuring the immersion heated is fully submerged in the oil. Thirdly there could be inaccurate readings of the thermometer, which can be avoided by using an electronic temperature probe And lastly, thermal energy may not be spread evenly through the oil which can be reduced by stirring the oil |
| What are the advantages of fossil fuels? | Fossil fuels are reliable because they always provide energy when needed, they release a great deal of energy which can be useful in the case of aeroplanes that use jet fuel made from oil, in addition to this fossil fuels are abundant and relatively cheap, and they are extremely versatile: they can be used for heating, transportation and generating electricity |
| What are the disadvantages of fossil fuels? | Burning fossil fuels releases a huge amount of carbon dioxide, they are non-renewable which means they aren’t being replenished/replaced as we use them. Fossil fuels can also increase other pollutants such as burning diesel in cars and trucks that releases carbon particles and nitrogen oxide |
| What is a key fact about nucleic power? | Nuclear power is non-renewable, when the nuclear power plants run they releases carbon dioxide, they run on elements such as uranium and plutonium |
| What are the advantages of generating electricity by nuclear power? | Once the nuclear power is running isn’t doesn’t release carbon dioxide, it is extremely reliable and generates a lot of electricity when wanted. |
| What are the disadvantages of generating electricity with nuclear power? | Nuclear power plants contain highly dangerous radioactive materials and if there is an accident these materials could be released into the environment. At the end of its life, a nuclear power plant has to be decommissioned or dismantled which can take up to many years and is extremely expensive. During the life and after decommissioning of nuclear power plants, generate large amounts of highly dangerous radioactive waste which must be stood for thousands of years before it’s safe |
| What’s an example of the effect of radioactive materials in nuclear power plants? | An example of the radioactive materials in nuclear power plants was in Japan, 2010, when a tsunami flooded the power plant, resulting in the release of radioactive material; over 150,000 people who lived in close proximity has to be evacuated and the clean-up/removal lasted many years. |
| Describe how the use of energy resources in the UK is changing | During the 1970s scientists began to realise carbon dioxide emissions could be leading to climate change, however, politicians didn’t see this as a serious issue. And energy from fossil fuels was valued for the economical factor of its inexpensiveness, while switching to renewable to alternatives costed money and therefore jobs. However, in 2005, the Kyoto protocol committed countries to reduce greenhouse gas emissions. The UK has one of the best locations for wind power in the world, over the last decade, the UK has opened a large number of wind farms. Other remunerable energy sources such a solar power and biofuels are increasing in the UK. The UK’s future looks upon renewables providing the bulk of our electricity while nuclear power produces the base-load and gas provides electricity during periods of peak demand. |
| Define Renewable energy | A Renewable energy resources is one that is being (or can be) replenished as it is used |
| Give seven different types of renewable energies | Renewable energy resources include wind power, solar power and hydroelectric power, tidal power, biofuels, geothermal and wave power. |
| What are the advantages of Renewable energy resources? | Renewable energy resources do not run out and once in place, renewable energy resources don’t add carbon dioxide to the atmosphere. |
| What are the disadvantages of renewable general energy resources? | Renewable energy resources such as wind power and solar power are not reliable, as they fully depend on the irregular non-fixed patterns of the weather, while hydroelectric power is reliable, however habitats are destroyed when dams are built and valleys are flooded. In addition to this hydroelectricity is only useful in countries which have lots of rivers. |
| What are the advantages and disadvantages of tidal power? | Tidal power is very reliable but currently the UK doesn’t generate any electricity from tidal power, but there are proposals to build a tidal barrage cross the severn estuary which some people argue could be harmful to wildlife. |
| What are the nine energy stores? | The nine energy stores are LSG Cenek, or Light, Sound, Gravitational potential energy, Chemical, Electrical, Nuclear, Elastic potential energy, and Kinetic |
| What are the advantages of wave power and geothermal power ? | Wave power is reliable and has potential in the UK because it has an extensive coastline. While geothermal energy that uses heat from the earth to generate electricity and heat buildings, is reliable but not commonly used in the UK. |
| How are biofuels produced and what are its advantages? | Biofuels are produced from a plant material, these plants tuck in carbon dioxide and they don’t add extra carbon dioxide to the atmosphere, therefore they are carbon neutral. Biofuels are very useful as we can use them to power vehicles such as cars and busses |
| What’s the problem with biofuels? | The problem with biofuels is that they use land to grow crops for fuel which could increase decreases for supply and therefore increases the cost of food/crops |
| How are the particles in a solid arranged? | The particles in a solid are packed together in a fixed arrangement with minimal spaced between then and strong intermolecular forces masking them not easily compressible. And the particles in a solid vibrate on the spot at a low energy allowing then to maintain their shape and from easily |
| How are the particles in a liquid arranged? | The particles in a liquid are close together with minimal spaces and weak intermolecular forces making them not easily compressible. The particles in a liquid have more energy than a solid allowing liquids to flow and take the shape of their container. |
| How are the particles in a gas arranged? | The particles in a gas are widely spaced with no intermolecular forces or regular arrangement which makes them easily compressible. And particles in a gas move quickly and randomly with high amount of energy allowing gasses to spread out and fill the space of their container |
| What is the equation for density? | D = m / v Density (km/m^3) = m (kg) / volume (m^3) |
| How high is the density of a solid, liquid and a gas? | Solids and liquids have a very high density, but gases have a low density. |
| How much mass do solids, liquids, and gases have for their volume? | Solids and liquids have a lot of mass for their volume because their particles are packed closely together Whereas gases have a small mass for their volume because their particles are very far apart |
| How high is the density of a gas? | Gasses have a low density. |
| What solid has a low density? | Polystyrene is a solid with a low density because it has a very open structure and is full of air spaces, therefore it also has a small mass for its volume |
| How much mass do gases have for their volume? | Because the particles are very far apart, gases have a small mass for their volume |
| How easy are the dimensions of regular and irregular objects to measure? | Regular objects have dimensions that are easy to measure, for example a cube can be measured with a ruler, but irregular objects have dimensions that are not easy to measure such as a vase |
| How is the volume of an irregular object measured? | The volume of an irregular object is measured using displacement. This is done by filling a Eureka can with water and the Eureka can has a spout so water can flow out of the can. The irregular object is now placed in the water and the water will become displaced and flow out through the spout (Into a measuring column) The volume of water displaced is measured using a ruler and the volume of the water is the same as the volume of the object |
| What is potential energy? | Particles have potential energy which are the intermolecular forces and chemical bonds |
| What is sublimation? | Sublimation is when a solid directly changes to a gas, such as in the case of carbon dioxide at room temperature |
| What happens to mass when changed of state take place? | When changes of state take place, mass is always conserved, which means that particles are not added or subtracted |
| What is internal energy? | Internal energy is the energy stored in a system by the particles |
| What is internal energy the total of? | Internal energy is the total kinetic energy and potential energy of all the particles that make up a system |
| What happens to the internal energy when a solid is heated or a liquid is boiled? | If a solid is heated or a liquid is boiled the internal energy is increased |
| What happens to the internal energy when a gas is cooled down? | When a gas is cooled down the internal energy is reduced to a liquid through condensation |
| Are changes of state physical or chemical changes, and what does this mean? | Changes of state are physical changes which means that if the changes are reversed the material recovers it original properties |
| What is evaporation? | Evaporation is when only the surface particles of a liquid turn into a gas |
| What eqaution is specific heat capacity used in? | Specific heat capacity is used in the change in thermal energy eqauation |
| What is latent heat? | Latent heat is the energy required for a substance to change |
| What does the line on a heating graph look like? | The line on heating graph looks like a diagonal line, then a horizontal line, then a diagonal, a horizontal line and a final diagonal line all, with the whole line pointing right |
| What happens on a heating graph? | In a heating graph a solid’s particles are melted into a liquid, the liquids particles are then further heated to boil into a gas and the gasses particles are further heated, shown at the end of the graph |
| Where are the melting and boiling points on a heating graph located? | On a heating graph the melting and boiling points are located on the first and second horizontal line |
| What happens in a cooling graph? | In a cooling graph a gas is condensed to a liquid and this liquid is frozen to a solid |
| When is the temperature constant on a heating graph? | The temperature is constant on a heating graph when a substance changes state |
| Why does the temperature of a substance become constant when it melts? | When a substance melts the temperature becomes constant because the energy put in is breaking the forces of attraction between the particles |
| What is latent heat? And what is the specific latent heat of fusion? | Latent heat is the energy required for a substance to change state And the specific latent heat of fusion is the energy require to change 1kg of a substance from a solid to a liquid without changing the temperature |
| What is the change in thermal energy equation? | Change in thermal energy (J) = Mass (kg) x Specific heat capacity (J/Kg degrees C) x Temperature change (degrees C) |
| What is the equation of the energy for a change of state? | E = m x L Energy for a change of state (J) = Mass (kg) x Specific latent heat (J/Kg) |
| What is the pressure created by? | The pressure of a gas is created by particles colliding at right angles with the walls of the container the gas is held in |
| How can the pressure of a gas be increased? | The pressure of a gas can be increased by increasing the number of collisions per second or by increasing the energy of each collision, one way to do this is by increasing the temperature of the gas |
| What is the temperature of a gas directly proportional to? | The temperature of a gas is directly proportional to the average kinetic energy of the particles |
| Why do gasses have a low pressure at low temperatures and why do they have a high pressure at high temperatures? | At low temperatures, gases have a low pressure because the particles have a lower kinetic energy so there are fewer collisions per second Therefore, at high temperatures, gases have a high pressure because the particles have higher kinetic energy so there are more collisions per second |