Physics- Energy and Motion

• Created by: Jasmin3
• Created on: 03-04-18 09:35
What are the eight different types of energy store?
Thermal, Kinetic, Gravitational Potential, Nuclear, Elastic, Chemical, Magnetic, Electrostatic
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What is a 'system' in terms of energy transfer?
A fancy word for a single or group of objects that you're interested in.
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When a system changes, energy is transferred. In what two ways can energy be transferred?
Either into or away from the system.
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When a kettle is being boiled, what way is energy being transferred?
By heating it.
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Work done is the same as energy transfer. When is work done completed?
When a current flows or by a force moving an object.
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In terms of energy transfer, what happens when someone throws a ball in the air?
Chemical energy sore from the perosn's arm transfers to kinetic (movement) energy of the ball and arm.
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In terms of energy transfer, what happens when a car hits its brakes?
Friction slows the tyres. Energy transfers from the wheel's kinetic energy to thermal energy into the ground and surroundings.
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If something is moving, what energy store does it have? If energy is transferrred to or away from this store, what happens to the moving object?
Kinetic energy, transferrred to speeds it up, transferred away, slows it down.
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What two things does the energy in the kinetic energy store depend on?
Mass and speed. More mass, faster its going, the more energy.
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What is the formula for kinetic energy?
Kinetic Energy (J) = 0.5 x Mass (kg) x Speed squared (m/s)2 Ek=1/2mv2
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What causes an energy transfer in gravitational potential energy?
Lifting an object.
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What 3 factors can change the amount of energy in gravitational potential energy?
Mass, Height and (Gravitational Field) Strength
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What is the formula for Gravitational Potential Energy?
G.P.E (J) = Mass (kg) x Gravitational Field Strength (N/kg) x Height (m) Ep = mgh
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What energy transfer happens when an object falls? What about when there is no air resistance?
Gravitational Potential Energy is transferred into kinetic energy stores Energy lost from g.p.e is energy gained in kinetic..
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Stretching or _________ an object can transfer energy to _______ potential energy.
Squashing , Elastic
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What can not be exceeded for energy to be stored in elastic potential energy?
The limit of proportionality.
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What is the formula for elastic potential energy?
E.P.E (J) = 0.5 x Spring Constant (N/m) x Extension squared (m) Ee = 1/2ke2
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A 2.0kg object falls 5m. Pressuming no air resistance, calculate the speed of the object. 5 marks.
Ep = mgh = 2 x 9.8 x 5 = 98J. Ek = 1/2mv2. v2 = 2Ek / m. = (2 x 98) / 2 = 98 m2/s2 (5)
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What is the conservation of energy principle?
Energy can be transferred, but never created or destroyed.
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What is 'wasted energy'?
In a transfer most energy is usefully transferred to another sorce however waste energy is the bit that is lost, turned into other smaller, less useful sources.
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Give an example of 'wasted energy'?
A kettle- mostly thermal energy in the water, wasted energy includes into the light on the kettle or kinetic into the environment.
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What is power?
The rate of energy transfer or the rate of doing work.
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Watt is power measured in? 1 Joule = How many?
Watts. 1 Joule = 1 Watt
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What are the two equations for power?
Power (W) = Energy Transfer (J) / Time (s) P = E/T OR Power (W = Work Done (J) / Time (s) P = W/T
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A motor transfers 4.8 kJ of energy in 2 minutes. Calculate it's power output.
4.8 kJ = 4800J. 2 minutes = 120 s. 4800/120 = 40. 40 W.
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What is conduction? Which state of matter is it most common?
A process where vibrating particles transfer energy to neighbouring particles. Mainly occurs in solids.
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When solids are hot particles vibrate ____ and ______ with each other. These __________ cause energy transfer between particles kinetic store. This process is called __________.
more , collide, collisions, conduction
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Energy transfer occurs in an object until what?
Thermal energy is released to the surroundings meaning it has cooled down.
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What is thermal conductivity?
A measure of how quickly energy is transferred through a material.
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What states of matter does convection occur?
Liquids and gases
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How does convection transfer energy?
By heating the thermal store which is shared through particles in kinetic energy form.
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Wht are particles in liquids and gases able to do that solids can't?
They can move, when you heat a region they will move quicker also.
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What happens if you heat a liquid or gas in terms f energy and particle movement?
They move quicker meaning space between particles increase and density decreases. Warmer and less dense areas will rise above cooler and denser areas.
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How do you create a convection current?
By giving a constant heat source.
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Describe how energy is transferred through a solid by heating? What is the name of this effect?
It is called conduction (1). Heating transfers energy to the particles kinetic energy stores (1). These particles collide slowly transferring energy between them in the form of kinetic (1).
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What is Insulation?
The reduce of the rate of energy transfer by heating.
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Name 1 form of house insulation and how it helps.
Thick walls - Made from material with low thermal conductivity. The thicker the walls the lower the thermal conductivity, the slower the rate of energy transfer (they will cool slower).
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How would you define an efficent device? How can you improve effiicency?
Somthing that wastes a really small amount of energy. Insulate it.
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What is the efficency formula?
Efficency = Useful output energy transfer / Total input energy transfer
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True or False; Some materials are 100% efficent. Why?
False. There is always 'waste' energy in a transfer, it usually goes to waste thermal energy.
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A motor transfers 300J of energy to the car's energy store. 225 J are transferred to the car's kinetic energy stores. Calculate the efficency.
225/300 = 0.75
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What is the difference between a renewable and non-renewable energy source?
Renewable will never run out, non-renewable will run out some day and can't be replaced.
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Name 3 non-renewable energy sources and 5 renewable energy sources.
Non-renewable: Coal, Oil, (Natural) Gas. Renewable: Tidal, Wind, Solar, Nuclear, Water Waves, Hydro-electricity, Bio-fuel and Geothermal
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How are cars effected my non-renewable energy resources?
They run on petrol and diesel (mainly) which come from oil, which will run out.
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Name 2 pros and 2 cons of Wind Power.
Pro: No pollution, Minimal running costs, no permanent damage. Cons: Initially expensive, Very noisy, Spoil the view
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Name 2 pros and 2 cons of Solar Power.
Pros: Used in remote places, no pollution, very reliable always work in daytime. Cons: Cost is high to set up, Can't increase power output.
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Name 2 pros and 2 cons of Geothermal Power.
Pros: Free energy, reliable, little damage on environement. Cons: Not many suitable locations, cost is high, supplies little energy.
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Name 2 pros and 2 cons of Hydro-electric Power.
Pros: No pollution, Immediate response for electricity. Cons: Causes flooding, loss of habitat, costly.
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Name 2 pros and 2 cons of Wave Power.
Pros: No pollution, Very useful on small islands. Cons: Costly, damage sea beds, unreliable.
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Name 2 pros and 2 cons Tidal Power.
Pros: No pollution, Reliable. Cons: Alter habitats, costly, don't produce much energy.
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What are bio-fuels?
Renewable energy sources that can be burnt to produce electricity, same as fossil fuels. Are carbon neutral, relable but costly.
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Are non-renewable energy sources reliable?
Yes because they can respond quickly to changes in demand but they are slowly running out.
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Other cards in this set

Card 2

Front

What is a 'system' in terms of energy transfer?

Back

A fancy word for a single or group of objects that you're interested in.

Card 3

Front

When a system changes, energy is transferred. In what two ways can energy be transferred?

Card 4

Front

When a kettle is being boiled, what way is energy being transferred?

Card 5

Front

Work done is the same as energy transfer. When is work done completed?