# Physics- General Physics

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• Created by: Kitsune
• Created on: 22-02-17 10:26
What two instruments do we use to measure very small lengths?
Micrometer screw gauge, vernier calipers
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How to find a volume of an irregularly shaped object?
Use a measuring cylinder which contains a liquid. Find the volume by displacement.
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What is mass?
The amount of matter something is made of
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What is density?
The ratio of mass to volume or how concentrated the matter is
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What do you measure time with?
Stopwatch/stop-clock
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How would you measure the thickness of one paper sheet with a ruler?
Measure the thickness of several pieces and then find the average
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What is speed?
Distance travelled by an object in a unit of time
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What is acceleration?
The rate at which the velocity changes
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What is velocity?
Speed in a particular direction
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What type of quantity is velocity?
Vector
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What do vectors have?
Magnitude and direction
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Acceleration is ..... if the line on the graph is straight
Constant
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What is weight?
Gravity acting on an objet's mass
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What type of quantity is weight?
Vector
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What is the force that exists when two objects touch?
Contact force
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What direction does friction act in?
One that is opposite to motion
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Name the force that exists when an object is falling through air
Drag/air resistance
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What is the upward push of liquids?
Upthrust
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What are forces measure in?
Newtons
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How do we show that a force is vector?
With an arrow
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What is the resultant force?
A single force that has the same effect as two or more forces
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What happens when there is no resultant force?
There is no acceleration so an object will either stay at rest or move at a constant speed
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Why does an object accelerate when it falls?
The force of gravity is acting upon it
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Why does every object fall with the same acceleration?
The Earth pulls every kilogram with the force of 10N
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What is the acceleration of free fall?
Acceleration caused by the Earth's gravity field
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What field is close to the Earth's surface?
Uniform gravitational field
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Describe how an objects reachers terminal velocity
Air resistance affects acceleration and eventually it balances the object's weight so it stops accelerating at moves at a steady speed
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What force does an object moving in a circle experience?
Centripetal force
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Where does the force that keeps an object moving in a circle act?
Toward the center of the circle
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What is force?
The action of one body on another that causes its velocity to change
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What is a newton?
The force required to give a mass of 1 kg an acceleration of 1m/s^2
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What two things does the effect of a force depend on?
How big it is and how long it lasts for
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What is mv or mu in the impulse equation?
Momentum
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What is an impulse?
A change in momentum
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What is the principle of conservation of momentum?
Total momentum before= total momentum after
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What do vectors have?
Magnitude and direction
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Give 5 examples of scalar quantities.
Mass, temperature, speed, density, energy
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What is a pivot?
The fixed point about which an object turns
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What is a moment?
The turning effect of a force
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When is the moment greatest?
When the force acts at 90 degreed to the object and is far from the pivot
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In equilibrium there is no...
resulting force
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What is the principal of moments?
Total clockwise moment= total anti clockwise moment
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What do you call a plain piece of card?
Plain lamina
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What is the weight you can hang on a pin called?
Plumb-line
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Forces can change the ... and ... of the body
Shape, size
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How are stretching forces called?
Tensile
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How are compressive forces called?
Compressing
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How are twisting forces called?
Torsional
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What do you call the weight at the end of the spring?
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What do you say about a spring when it can no longer return to its original length?
It is inelastically deformed
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What do you call the length to which the spring increases?
Extension
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What is the point after which the spring can't return to its original shape?
Limit of proportionality/ elastic limit
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What is Hooke's law?
The extension of a spring is proportional to the load applied to it if the proportionality limit isn't exceeded
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What is the formula for Hooke's law?
F= kx
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What is k in Hooke's law
The spring constant, how stiff the spring is
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What is x in Hooke's law?
The extension
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Why does pressure increase as you go down in a liquid?
More weight is pressing down
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What is a manometer?
A simple u shaped instrument that shows the difference in pressure
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Where can a manometer measure pressure?
In liquids and gases
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What is a barometer?
A device used to measure atmospheric pressure
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What is a barometer filled with?
Mercury
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How do you set up a barometer?
You invert the tube and place it in a trough containing mercury. The level of mercury in the tube falls.
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In a barometer, the higher the atmospheric pressure...
the higher the level of mercury in the tube
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Why is mercury used in a barometer?
It has high density
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What is pressure?
Force/area
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To increase pressure...
decrease the surface area
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What is that other formula for pressure?
P= ghp
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Where is nuclear energy stored?
In a nucleus of a radioactive atom
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What energy is stored in hot objects?
Internal energy
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What energy do hot objets emit?
Thermal and light
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What are the 4 ways of transferring energy?
By force, by heating, by radiation and by electricity
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What diagram do we use to show energy change?
Sankey diagram
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Why is energy never fully converted into its useful form?
Some is always wasted.
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What are the two most common forms of energy waste?
Heat and sound
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What is the principle of conversion of energy?
Energy cannot be created or destroyed, only transformed from one form to another
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What is efficiency?
An energy fraction that is in desired form
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What is the source of energy for all energy sources?
The sun
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Give two advantages of solar energy.
It's renewable and doesn't cause pollution
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Give two disadvantages of solar energy.
It is expensive and weather dependent
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What devices collect solar energy?
Solar panels and solar cells
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How do solar panels collect and use solar energy?
They absorb solar rays, heating water inside the panel and making steam
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To what energy do solar cells convert solar energy?
Electrical energy
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What are the uses of solar energy?
Powering space craft, roadside emergency panels, medicine refrigerators
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Why does the sun release energy?
At high temperature and pressure hydrogen atoms collide and form helium. This process is nuclear fusion
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Give examples of biomass fuels.
Wood, biomass, animal dung
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What are the two advantages of biomass fuels.
Renewable and easy to use
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Give a disadvantage of biomass fuels.
A large area is required
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What is the energy change when biomass fuels are burn?
From chemical to heat
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Most of wind energy is given up to...
the sea as waves by friction between air and water
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What are the 2 advantages of wind energy?
It is renewable and doesn't cause pollution
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What are the 3 disadvantages of wind energy?
Machines are ugly and noisy, expensive, weather dependent
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What devices collect wind energy?
Windmills and wind turbines
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What is the energy change when wind energy is used?
Kinetic to electrical
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Name the three fossil fuels
Oil, gas and coal
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What is the energy change when fossil fuels are burnt
Chemical to heat
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What are the three advantages of using fossil fuels?
Stable, cheap, easily available
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What are the two disadvantages of using fossil fuels?
Non-renewable and affect health
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What is a common source of nuclear energy?
Uranium 235
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What are the 2 advantages of using nuclear fuels?
Relatively cheap, releases a lot of energy
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What are the 2 disadvantages of using nuclear fuels?
Dangerous and non-renewable
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How does hydroelectric power work?
Water from the dam is released to turn turbines, generators spin and electricity is produced
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What are the 2 advantages of hydroelectric power?
Clean and stable
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What are the 2 disadvantages of hydroelectric power?
expensive and can ruin environment
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What is the energy change when using hydroelectric power?
Kinetic to electrical
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What is the energy change when using tidal energy?
G.p.e. to electrical
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How is geothermal energy obtained?
There are hot rocks below the Earth's surface. Water is pumped down to them where it boils and rises as steam. This steam is used to generate electricity.
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What are the two advantages of geothermal energy?
It is renewable and doesn't cause pollution
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What are the two disadvantages of geothermal energy?
It is expensive and there aren't many places where it can be obtained
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What does work done equal to?
Energy transferred
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What does the amount of energy transferred by a fore depend on?
The size of the force and the distance moved in the direction of a force
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What is work does measure in?
Joules
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What is power?
The rate at which energy is transferred
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What are the two ways of increasing power?
Lift a heavier object or lift it faster
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What is power measure in?
Watts
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## Other cards in this set

### Card 2

#### Front

How to find a volume of an irregularly shaped object?

#### Back

Use a measuring cylinder which contains a liquid. Find the volume by displacement.

What is mass?

What is density?

### Card 5

#### Front

What do you measure time with?