Flashcards in Topic 1- Motion, Forces And Conservation Of Energy Deck (49):
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8 Energy stores
Kinetic, Thermal, Chemical, Nuclear, Magnetic, Electrostatic, Elastic Potential, GPE
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Kenton energy depends on...
Mass and speed
Greater the mass and the faster it’s going, the more kinetic energy
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If you double the mass, the energy in the kinetic energy store...
Doubles
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If you double the speed, the energy in the kinetic energy store...
Quadruples
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Energy can be ... , ... between stores and ...
But can never be ... or ...
The total energy of a closed system has...
Stored, transferred and dissipated
Can never be created or destroyed
No net charge
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Energy can be transferred between stores in four main ways...
Mechanically
Electrically
By heating
By radiation
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A ball rolling up a slope
The ball does work against the gravitational force
So energy is transferred mechanically from the mentor energy store of the ball to its gravitational potential energy store
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A bat hitting a ball
Bat has energy in its kinetic energy store
Some out this is transferred mechanically to the balls kinetic energy store
Some is also transferred mechanically to the thermal energy stores of the bat, ball and surroundings
The rest is carried away by sound
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Energy is only useful when...
It is transferred from one store to a useful store
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Input energy is always ... and ... to the surroundings
Dissipated or wasted
Often to thermal energy stores
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When work is done mechanically ... have to be overcome eg.
Therefore...
Frictional forces eg. Things rubbing together and air resistance
Therefore energy needed to overcome this is transferred to thermal energy stores (not useful energy)
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What reduces unwanted energy transfers
Lubricants- reduce friction between objects when they move usually liquids like oil, can flow easily between objects and coat them
Insulation- between walls of houses, lowest conductivity means slowest rate of energy transferred through them (thick walls and a air gap between the two walls)
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Non renewable advantages
Reliable- can meet the current demand, use more fuel to release more energy
Cheap to build and run fossil fuel power plants
Low cost of extracting fossil fuels
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Disadvantages of non renewable
Nuclear power plants cost a lot to build and cause safety issues
Slowly running out
Environmental problems, contribute to global warming
Cause acid rain
Oil spillages
Nuclear waste is dangerous
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Renewable advantages
Never run out
Not as much impact on environment
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Disadvantages of renewable
Don’t provide much energy
Not efficient
Weather dependant
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Biofuels
Made from plants and waste
Can not respond to immediate energy demands
Cost lots
Increases methane and carbon dioxide emissions
Reliable because crops grow quickly
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Wind power
Initial costs are high but minimal to run
No pollution
Lots of them are needed to produce lots of power
Spoil the view
Noisy
Only work when wind so can’t always supply to high demand
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Solar cells
No pollution
Initial costs are high but minimal to run
Generate small scale electricity
Most suitable for sunny countries
No power made at night
Can’t increase production when there is extra demand
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Hydro-electricity
No pollution
Big impact on environment due to flooding possible loss of housings or habitats
Immediately respond to increased electricity demand
Initial costs are high but minimal running cost
Generally reliable
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Tidal barrages
No pollution
Effect boat access
Can spoil view
Alter wildlife
Reliable
Don’t work when water levels are equal both sides
Initial costs are high but minimal running costs
No fuel costs
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Vectors...
Have a magnitude (size) and direction
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Vector quantities
Force
Velocity
Displacement
Weight
Acceleration
Momentum
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Scalar
Only have a magnitude and no direction
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Scalar quantities
Speed
Distance
Mass
Energy
Temperature
Time
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Speed is...
Just how fast something is travelling with no regard to direction
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Velocity is ...
Speed in a given direction
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Distance is...
How far an object has moved
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Displacement is ...
A measurement of direction and distance in a straight line from a starting point to its finishing point
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Acceleration is ...
The change in velocity in a certain amount of time
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Deceleration is ...
Negative acceleration
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Constant acceleration can also be called
Uniform acceleration
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Example of uniform acceleration
Acceleration due to gravity
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Acceleration equation
a = (v-u) / t
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Uniform acceleration equation
(v)2 - (u)2 = 2 x a x X
The 2s around the brackets = squared
The small x = multiply
Large X = distance
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Distance- speed graph :
What does the gradient mean
Flat sections
Curves
Gradient at any point gives the speed
Flat sections is where the object has stopped
Curves are represent acceleration, the steeper the curve the greater the acceleration and if the curve sloops off the slower the acceleration
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Finding speed from a distance - time graph
The gradient = speed
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Velocity- time graphs :
Gradient
Flat sections
Up
Down
Curve
Gradient = acceleration
Flat sections = steady speed
Up = acceleration
Down = deceleration
Curve = changing acceleration
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How to get distance from a velocity- time graph
The area underneath the graph is the distance travelled
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Momentum is ...
A property that all moving objects have. Defined as a product of an objects mass and velocity
Vector quantity - has size and direction
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Greater mass or velocity
Affect on momentum
Increases
More momentum
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Total momentum before = ?
Total momentum after
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What is conservative of momentum
The momentum being the same before and after an event
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Newton’s first law
If the resultant force of a stationary object is zero, the object will remain stationary.
If the resultant force on a moving object is zero, it’ll just carry on moving at the same velocity.
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A non zero resultant force will ...
Always produce acceleration or deceleration in the direction of the force
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Acceleration is proportional to...
therefore...
Resultant force
Therefore the more an object accelerates the larger the resultant force
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Newton’s second law
Resultant force = mass x acceleration
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Acceleration is inversely proportional to...
therefore...
The mass of the object
Therefore the larger the mass, the slower the acceleration
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