Physics Unit 2

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What is the speed if an object?
The distance traveled each second
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What does the gradient of a distance time graph represent?
Speed
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How is a stationary object showed on a distance time graph?
The line is horizontal if the object is still
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What is velocity?
Speed in a given direction
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What do we say when the velocity changes?
We say the object has accelerated
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What do we call a negative acceleration?
Deceleration
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What does the gradient of the line on a velocity time graph show?
Acceleration
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What does a horizontal line on a velocity time graph show?
Constant speed because there is no acceleration
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What does the area under the line on a velocity time graph represent?
Distance traveled in a given time
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What is force measured in?
Newtons (N)
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Objects all ways exert ..... and ..... forces on eachother
Equal and opposite
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What is the resultant force?
The single force that would have the same effect on the object as all the original forces acting together.
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What will happen if the resultant force is zero and the object is a rest?
It will stay at rest
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What will happen if the resultant force is zero and the object is moving?
Carry on at the same speed in the same direction
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If the resultant force is not zero, what will happen?
There will be an acceleration or a deceleration
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Th bigger the resultant force, the greater the what?
Acceleration
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The larger the mass the larger the what?
force needed to give an acceleration
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What is stopping distance?
The distance a vehicle travels during the drivers reaction time (thinking distance) plus the distance it travels under the braking force (braking distance)
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What is terminal velocity?
Velocity and object reaches when it is falling in a fluid. The weight is the equal to the drag force on the object.
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What is the extension of a spring directly proportional to?
Force applied
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What is Hooke's law?
the extension is directly proportional to the force applied provided the limit of proportionality is not exceeded.
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What is fuel economy?
Reducing the speed of a vehicle reduces the amount of fuel used to travel a particular distance/
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What must happen for an object to move?
A force must have been applied
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What happens when a force moves an object?
Energy is transferred and work is done
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What has the unit joule?
work and energy
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What is power?
The rate of energy transfer
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The greater the mass and the faster the speed of an object the more what?
Kinetic energy the object has
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What is elastic potential energy?
Energy stored in an elastic object when work is done to change shape
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What is momentum affected by?
Mass and velocity
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What is the conservation of momentum?
The momentum before an interaction is equal to the momentum after providing no external force acts on the objects.
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Momentum has both what and what?
size and direction
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What is the momentum when an object is at rest?
0
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As impact time increases, what happens to the forces?
They reduce
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How do crumple zones work?
They are in cars and fold in collisions. They increase impact time and reduce the force on the car and the people in it
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How do seat belts and air bags work?
Spreads the force on the body across the larger area and the airbag changes momentum slowly so there is less force
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What happens when 2 electrically insulating materials are rubbed together?
Electrons are rubbed off one material and transferred to the other.
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Opposite electrical charges do what?
Attract
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the bigger the distance between two objects the weaker the what?
Force between them
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How do we measure current through a component?
Using an ammeter
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Where are ammeters placed in circuits?
In series with the component
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How do we measure the potential difference?
Voltmeter
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Where are voltmeters placed?
In parallel with the component.
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What is resistance?
the opposition to current flow
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What is ohm's law?
Current is directly proportional to the potential difference
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Describe the current through a diode?
It only flows in one direction
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What happens to the resistance of a thermistor as the temperature goes up?
Goes down
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What happens is there is a break in a series circuit?
The charge stops flowing because all the components are all connected one after the other.
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What is an advantage of a parallel circuit?
Each component is connected across the supply so any break in the circuit doesn't affect the rest of the circuit and components.
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What is the total current of a parallel circuit equal to?
The sum of the current through the separate components.
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what do cells and batteries supply?
current that passes around the circuit in one direction.
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what happens to the current through the main supply?
passes in one direction then reverses and goes in the other direction.
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what is the frequency of the UKs mains supply?
50 hertz
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what is the potential of the live wire?
Alternates between positive and negative
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what are the three wires in a plug socket?
Live, neutral, earth
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what colour is the live wire?
Brown
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What is the colour of the earth wire?
green and yellow
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why does a mains appliance with a plastic case not need to be earthed?
Plastic is an insulator and can not become live
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what does a fuse do?
cuts the appliance off from the live wire if the fuse is blown
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What is an electric current?
Rate of flow of charge
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what may cause an electric fault?
Damaged sockets, cables or plugs
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what is special about the nuclei of a radioactive substance?
Unstable
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what are the three types of radiation?
Alpha Beta and Gamma
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What happened in the "alpha particle scattering experiment"
they fired apha particles at thin gold foil. Most went through, some were deflected and some rebounded
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what is the relative mass of a proton?
1
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what is an isotope?
Atoms of the same element with different numbers of neutrons
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what is the charge of alpha particles?
positive
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What is half life?
It is the time it takes for the count rate of the original isotope to fall to half its initial value.
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What is a use of Gamma and beta sources?
Tracers in medicine
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What can be used to date ancient materials?
Radioactive dating
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What is alpha used for?
smoke alarms
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What is nuclear fission?
The splitting of an atomic nucleus
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When does a chain reaction occur?
When a fission event causes further fission
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What is nuclear fusion?
2 nuclei get close enough to form a single one
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What is a source of background radiation?
Radon gas
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What is the basic idea of how a star is formed?
Dust and gass are puled together by gravitational attraction to form stars
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What is a galaxy?
Collection of billions of starts held together by their own gravity.
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What is the first star in a sequence called?
Protostar
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How are chemical elements formed?
Fusion stars in stars
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Other cards in this set

Card 2

Front

What does the gradient of a distance time graph represent?

Back

Speed

Card 3

Front

How is a stationary object showed on a distance time graph?

Back

Preview of the front of card 3

Card 4

Front

What is velocity?

Back

Preview of the front of card 4

Card 5

Front

What do we say when the velocity changes?

Back

Preview of the front of card 5
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