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Physics Paper 1, Energy can be stored, transferred or dissipated(released…

- - - - Elastic Potential Energy
        
        Stretched or bent objects have elastic energy, if they have the ability to recover to their original shape and dimensions. If for example a spring gets a weight (force) added to it, it will extend. That spring would now have a store elastic potential energy which will be released if the force on the spring is removed and it can go back to its original shape and dimensions
        
        Elastic Potential Energy (J) = 0.5 x spring constant (N) x extension ^2 (m)
        
        Example elastic potential energy question:
        A spring has a spring constant of 670 N/m. The spring with the force pulling it down is 0.075m longer than usual, so its extension is 0.075m. Calculate the elastic potential energy of the spring when a 50 N force is hung from
        1)We were given all the measurements so we just have to multiply it all together. 0.5 x 670 x 0.075^2 = 1.88 J
      - Gravitational Potential Energy (GPE)
        
        When an object is raised above ground, it gains gravitational potential energy. This stored energy is released if the object falls.
        
        GPE = mass (kg) x gravitational field strength (N/kg) x height (m) on the equations sheet.
        
        Example GPE question:
        A pile driver’s (a machine that drives poles into the ground by dropping a heavy hammer on them) hammer has a mass of 120kg and is raised 0.004 km above the ground. How much GPE will it have?
        1) Fix the height units: 1km = 1 000m so 0.004km = 4m
        2) The Earth’s GFS is 9.8N/kg (but we often, like in this example, round it to just 10)
        3) multiply everything 120 x 10 x 4 = 4800, so the GPE gained is 4800 J.
      - Kinetic Energy
        
        All moving objects have kinetic energy. The more kinetic energy something has, the further it will travel. Kinetic energy depends on the thing’s mass( which you might not be able to change) and the velocity (which can be increased by running faster for example)
        
        Kinetic energy = ½ x Mass (Kg) x Speed^2(m/s)
        not on equation sheet, but i know it. Could also be written as K.E. = 1/2 m v2
        
        Example kinetic energy question:
        If a person’s mass is 46 000g and she is travelling at 8m/s, what is her kinetic energy going to be?
        1) First we need to change the mass to kilograms. 1 000g = 1kg, so 46 000g = 46kg. The speed is already in m/s so we don’t need to change that.
        2) We now multiply everything together (0.5 x 46 x 8^2) to get 1472. The energy transferred is therefore 1472 J.
    - - definition = the rate (how quickly) at which energy is transferred OR the rate at which work is done.
      - measured in Joules / second
      - unit: Watt (W)
      - equation:
        Power(W) = Energy transferred (J) ÷ Time(s)
    - - Energy stores and examples on where to find them:
        Chemical- in food, fuel and electric batteries.
        Kinetic - in moving objects
        Gravitational Potential - in objects raised above a planets surface
        Elastic Potential - in stretched, compressed or twisted objects
        Internal (thermal) - in any heated object
        Magnetic - in an objet with a magnetic field
        Nuclear - the forces acting between atomic nuclei
        Electrostatic - in electrostatic forces between charges
        
        Forces travel in different ways. Force pathways include:
        Mechanically ( when a force acts and an object moves)
        Electrically (when an electric current flows)
        Heating (a temperature difference between objects)
        Radiation (through electromagnetic waves or sound)
        
        Mechanical Work: the amount of energy transferred by a force
        
        (Mechnial)Work done (J) = Force (N) x Distance (m).
        On the equations sheet. distance is along the line of force
        
        Example work done question:
        if an aircraft has a mass of 30 000 kg and it is moved a distance f 20m, calculate the work done by the pushback truck that moved the aircraft.
        1) we need to find the force, so we use the equation Force= mass x gravitational field strength. We know earth’s grav. field strength is 9.8 or 10, and we have the mass, so. We can multiply those together to ge the force, which is 300 000N.
        2) Now, we can multiply the force we calculated and the distance(20m) together to get the work done. 300 000 x 20 = 6 000 000J.
        
        link to trinitynewbury.fireflycloud.net
        
        Electrical Work:
        the amount of energy transferred when charge flows in a circuit.
        
        Energy Transferred = charge flow (couloms) x Potential difference (V)
        also on equations sheet. Charge flows equation is also on there.
        
        Example energy transferred question:
        in one minute, 30 coulombs of charge flow through the bulb when a potential difference of 3 V is placed across it. Calculate the work done (energy transfer)
        1) we have both of things we need and they’re in the correct units (so not in MV or anything), so we just have to multiply them together o get the answer. 3 x 30 = 90. The energy transferred is therefore 90 J.
  - - - Unwanted Energy Transfers
        
        Energy stores that aren’t useful.
        
        A way to reduce unwanted energy transfers:
        Thermal insulation
        
        All the energy used to heat a home is eventually transferred as thermal energy to the surroundings.
        
        Materials that have different Thermal Conductivity Values.
        
        high thermal conductivity = heat is transferrred through the material faster
        
        low thermal conductivity = heat is transferred through the material at a slower pace.
        
        Insulatiion materials have low thermal conductivity so they keep the heat in for longer and insulating the house better.
        
        Example:
        In an F1 car all the chemical energy (fuel) ends up as unwanted energy eventuall. This energy is often then given out to the surroundings. So in this example the (useful) chemical energy is turned into kinetic energy at first (useful) which then turns into thermal energy (useless in this case). This could be reduced so more of the chemical energy is turned into kinetic by adding lubricant to some parts of the car to reduce friction.
      - Closed Systems
        
        In a closed system all energy can be accounted for, even if the energy stores change.
        
        The diagram shows the energy transfer for a light bulb. All the chemical energy(100%) put in can be accounted for in light energy (90%) and thermal energy (10%). In this case the thermal energy isn’t useful so it’s the dissipated or wasted energy.
        
        In a closed energy system, energy can be transferred but NOT MASS. There is no change to the total energy in the system, the energy only travels through.