physics PPE
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64 questions
| 🇬🇧 | 🇬🇧 |
| What is the insulation method | 1. pour 80cm3 of hot water from the kettle to a beaker 2. place cardboard lid with thermometer inside to beaker so it’s bulb is in the hot water 3. record temp of water and start the stopwatch 4. record temp of water every 3 mins for 15 mins 5. repeat steps using different materials/more layers of material on the beaker 6. plot a graph of temp in degrees celsius against time taken in mins |
| What is the independent variable of this practical | The insulating material/ the layers of material |
| What is the dependent variable of this practical | The temperature decrease of water after a given time |
| Kinetic energy equation | 0.5 x mv^2 |
| Goes equation | E = mgh |
| What is the definition of power | The rate at which energy is transferred or the rate at which work is done |
| What are the two equations for power | Power = energy transferred (or work done) /time |
| Calc | 8000 W |
| Calc power of both motors | 12.5 W, 8.3 W |
| What are the equations for efficiency | Useful output energy transfer/total input energy transfer useful power output/ total power input |
| Calc | 0.05/ 5% |
| What is kinetic energy | The energy stored in moving objects |
| Equation for kinetic energy | Ke = 0.5 x m x v^2 Ke= J m= kg v= m/s |
| Calc | 0.06 kg |
| What is gravitational potential energy | The energy stored in an object due to its position above the earths surface |
| Equation for GPE | GPE= m x g x h GPE= J m= kg g= N/kg h= m |
| Calc | 7.35 J |
| What is a renewable energy resource | One that is being or can be replenished as it is used |
| What are the advantages of renewable energy as a whole | - they do not run out - they do not not add CO2 into the atmosphere or contribute towards global warming |
| Why might wind power and solar power not be totally reliable | Wind power relies on wind to turn turbines, not every day is windy, solar panel relies on the sun to generate electricity, not everyday is sunny enough |
| What is the major disadvantage of hydro electric power | Habitats are destroyed when dams are built and valleys are flooded, they are also no use in a place prone to drought |
| How does geothermal energy work | Uses heat from the earth to generate electricity and heat in buildings |
| What is the problem with biofuels | If we use land to grow crops for fuel, that could push up the price of food |
| Protons and neutrons of an alpha particle | 2 protons, 2 neutrons, similar to a helium nucleus |
| Work out | 237, 93 |
| Work out | 131, 54 |
| What is half life | The time it takes for the number of nuclei in a radioactive isotope to half |
| Solve | 25 counts/s |
| What is irradiation | Exposing an object to nuclear radiation |
| What happens when the nuclei of an atom splits after absorbing a neutron | It splits into two smaller, roughly identical daughter nuclei and emits 2-3 neutrons and gamma radiation |
| Why do people dealing with ionising radiation have to take more precaution | Ionising radiation can increase the chance of mutating cells and causing cancer |
| What is radioactive contamination | When unwanted radioactive isotopes end up on or in other materials, hazardous as radioactive isotopes decay and emit ionising radiation |
| What is the most ionising radiation | Alpha, it is strongly ionising but easily stopped by dead cells on surface of the skin, very dangerous if inhaled or swallowed |
| What other radiation is ionising | Beta, can penetrate though skin and body |
| Which radiation is least ionising | Gamma radiation, passes straight through body cells so theses a less chance of ionising and cell mutation |
| What is current | A flow of electrons through a conductor such as a wire |
| Equation for calculating energy | E= P x t E= J P= W t= s |
| What does resistance tell us | How much energy is required to push a coulomb of charge through |
| Calc | 2000W |
| Equation for resistance | V= IR v= V I= A R= ohms |
| Calc | 120s |
| Calc | 25 V |
| Equation for power | P= V x I P= W V= V I= A |
| Calc | 2.5 W |
| How to calculate power when current and resistance through a component is given | P= I^2 x R P= W I= A R= ohms |
| Calc | 8W |
| What is the specific heat capacity of a substance | The amount of energy required to raise the temp of 1kg of the substance by 1 degrees celsius |
| Specific heat capacity equation | ⃤. E = m x c x. ⃤0 change in thermal energy= J mass= kg specific heat capacity= J/kg°C change in temp= °C |
| Calc | 246510 J |
| Calc | 3 kg |
| Outline all the steps to the specific heat capacity practical | 1. place beaker on balance and set to 0, add oil to beaker and record mass of oil 2. place thermometer and immersion heater into the oil, read starting temp of oil 3. wrap beaker in insulating foam to reduce thermal energy transfer to surroundings 4. connect joule meter and power pack to immersion heater, time for 30 mins 5.read total number of joules of energy that passed into immersion heater and final temp of oil 6. calc specific heat capacity with C. ΔE/ (Δ0 ⨉ m) |
| Calc | 1670 J/kg°C |
| What are some sources or inaccuracy in the specific heat capacity practical and how would you prevent them | - thermal energy passing out of the beaker to the air, prevented by using an insulator with lower thermal conductivity - not all thermal energy from immersion heater passes through to oil, to prevent this, ensure that immersion heater is fully submerged - incorrect reading of thermometer, use electric temp probe - thermal energy not being spread in oil, stir the oil |
| What are the arrangements of particles within a solid | Particles are very closely packed, arranged in a regular pattern, particles vibrate but to not move place to place |
| Describe the arrangement of particles in a liquid | Particles are closely packed, not arranged in a regular patter, particles move place to place |
| Particles in a gas | Particles are far apart, not arranged in any pattern, particles move rapidly from place to place |
| Equation for density | P= m/v p= kg/m^3 m= kg v= m^3 |
| Calc | 500kg/m^3 |
| Why do solids have high densities | Particles are packed closely together, they have lots of mass for their volume |
| Why do liquids have high density | Particles are closely packed, they have a lot of mass for their volume |
| Why do gases late a low density | Particles are very far apart, they have a small mass for their volume |
| What can happen is electrostatic charge builds up as fuel flows through a refuelling pipe | It could cause a spark and trigger an explosion |
| What happens if you rub a plastic rod with cloth | Electrons move from the plate onto the cloth, creating an overall negative charge on the cloth, because the plastic has lost electrons, the overall charge becomes positive |
| How does a van der graaf work | The moving belt moves and electrons pass from the top plastic roller to the belt and then the electrons pass from the belt and transfer to the earth, over time the top region becomes positive. the dome on top acts like a store of positive charge allowing the charge to spread out so if someone toughed it, they would have an overall positive charge so the hairs on their head all become positive and resell each other |
| What is internal energy | The energy stored in a system by particles, the total kinetic and potential energy of all particles that make up a system |
| What happens when you heat a solid to a liquid | You are increasing the internal energy and causing the solid to melt into a liquid. particles gain energy and start to vibrate faster so the structure is gradually weakened , as more energy is given to the particles, they start to break free of the structure |
| What happens when you heat a liquid to a gas | You increase the internal energy causing the liquid to evaporate. particles are given more energy to move faster and collide with each other, most energetic particles at the surface escape from surface as water vapour, as more energy is given to particles, they will break free from the structure |
| What happens when a gas condensates into a liquid | The internal energy of the gas decreases so it condensates. as the particles lose heat, they lose energy and slow down, the particles collect together and form a liquid |
| What happens to a liquid when it freezes into a solid | The internal energy decreases and causes the liquid to freeze. energy is released from the liquid into its surroundings as particles lose heat therefore energy and become a solid |