Motion, Forces And Energy Flashcards
What is the speed of light
3x10^8
What do you put on the x axis
The independent/input variable
What do you put on the y axis
The dependant/output variable
How can we ensure an accurate experiment result (3)
By taking a bigger sample size
Repeating the experiments more than 3 times and calculating an average
How can we measure the volume of a liquid
A measuring cylinder
How can we find the volume of a solid
By part filling a cylinder and noting the volume, then submerge a solid and not the new volume. The change in volume is the volume of the solid
How do you calculate the time for one oscillation
Total oscillations/number of oscillations
How do you calculate the thickness of a sheet of paper
Total thickness/number of sheets
What are scalars
Physical quantities with only magnitude
What are vectors
Quantities that have both magnitude and direction
What is momentum
An object’s resistance to stopping
What is the formula for momentum
p=mv
Is momentum a scalar or vector quantity
Vector
What is the SI unit for momentum
Kg m/s
What is impulse
Measure in change of momentum
What is force in relation to momentum
Give the formula
The rate of change of momentum
F=change in momentum/change in time
How does an airbag save lives
How does an airbag save lives
Can’t change impulse in car crash, but because airbag deflates upon impact, it increases the time for the momentum to be transferred and reduces the overall force on your body Can’t change impulse in car crash, but because airbag deflates upon impact, it increases the time for the momentum to be transferred and reduces the overall force on your body
What is the principle of conservation of linear momentum
When objects of a system interact, their total momentum before and after interaction are equal unless a net force acts upon the system
What is the principle of conservation of momentum
Total momentum of an isolated system in constant
What is the formula for the momentum of 2 objects that remain separate after collision
m1u1+m2u2=m1v1+m2u2
What is the formula for 2 objects that joined or liked up after interaction
m1u1+m2u2=(m1+m2)v
What happens to the velocity of 2 objects if they join during an interaction
They become equal
What happens to the total momentum during a collision
It is conserved
What happens to the masses of objects that join during an interaction
They combine
What are 2 very important rule to remember when calculating momentum
If moving in opposite directions, one velocity must be negative
You must state the direction of the object/s after interaction
What is the formula for kinetic energy
1/2mv^2
What is the formula for gpe
mgh
What 3 sources of energy do not come from the sun
Tidal
Geothermal
Nuclear
What is the turning effect of a force known as
A moment
When will the average and instantaneous velocity be the same
In the middle of the time
What is terminal velocity
The highest velocity attainable by an object falling through a fluid such as air or oil. It occurs when all the forces acting upon the object are equal. It has 0 acceleration
What is it called when an object undergoes an acceleration caused by gravity
Free fall
What is free-fall
Any motion of a body when gravity is the only force actung upon it
What is inertia
The tendency of an object to resist changes in motion
What is mass
The amount of matter in a body/measure of inertia in a body
It is dependant on the number if and the arrangements of atoms
It has a constant magnitude
What can be used to measure mass
Beam balance
Calibrated electronic balance
What is weight
The amount of gravitational force acting upon a body
Acts towards the centre of the earth
Depends on gravitational field strength
What can be used to measure weight
Scale balance
Calibrated electronic balance
Give an alternate way to measure the volume of an irregular object
Completely fill a eureka with water, measure what volume flowed over after the object was placed in
When will an object sink in water
When it has a density of higher than 1g/cm3
What may be caused by a force
A change in size,shape or motion of an object
What does an imbalance of forces acting upon an object cause
Acceleration/deceleration
How does mass effect a forces effect
The greater the mass of an object, the more force you need for the same change to the objects motion
What is Hooke’s law
The extention of a spring is directly proportionate to the force applied provided it has noy passed the limit of proportionality
What is the limit of proportionality
The point beyond which hookes law is no longer true
What does an object need to move in a cicular path
A force that acts perpendicular to the direction of the motion of the object, towards the centre of the circle
What are the conditions for an equilibrium
The total moments must be zero and the total net forces must be zero.
What is a lamina
Uniform sheet that has equal thickness throughout. Its centre of mass will always come to rest directly below the point of suspention
Provide an experiment to find the centre of mass of a lamina
-suspend shape from a location near an edge
-drop a plumb line(string with mass) and mark the line
-repeat from a new suspension point and mark the line
Where the lines meet is the centre of mass.
What is a plumb line
A string with mass
What is energy
the capacity of an object to do work
What is mechanical work
Forces transferring energy through
electrical currents(work)
Heating
Waves
What is kinetic energy
The energy of a moving object
What is gravitational potential energy
Energy of an object raised up against the formce of gravity
What is chemical energy
Energy stored in chemical substances that can be released in chemical reactions
What is chemical energy
Energy stored in a chemical substance that can be released during a chemical equation
What is elastic/strain potential energy
Energy that is stored when an object is stretched or compressed and is released when the contriction is.
What is electrical energy
Energy transferred by electric current
What is nuclear energy
Energy stored in the nucleus of an atom
internal energy
Sum of all kinetic and potential energies of all the objects particles
What is the principle of conservation of energy
The total energy of a closed system is constant provided no external force acts.
What do sankey diagrams represent
The flow and amount of energy in a system
What is work
Energy transfered
Related to magnitude of a force on a body and the distance moved in the direction of the force
Why is work done the same as change in gpe?
With no frictional forces you are only doing work against gravity
Why do we use slopes/ramps
Same work is done but over a greater distance, so the average force is much less, requiring less effort.
Weight
The effect of gravitational field strength on mass
Describe qualitatively, motion in a circular path due to a force perpendicular to the motion (3)
If speed increases force increases, radius and mass constant
If radius decreases force increases
Increased mass requires increased force to keep speed and radius constant
Limit of proportionality
The extension is no longer proportional to the force
Centre of gravity
The point through which an objects weight will act through
Experiment to determine position of centre of gravity of a lamina
Allow the card to swing freely from the pin. The card turns until the centre of mass is vertically under the pin. Repeat using a plumb line, and wherever the lines cross, this is the centre of mass.
Effect of the position of the centre of gravity on stability
The lower the centre of gravity, the more stable
Describe, qualitatively, motion in a circular path due to a force perpendicular to the motion
-speed increases if force increases, with mass and radius constant
-radius decreases if force increases, with mass and speed constant
-an increased mass requires an increased force to keep speed and radius constant
Centripetal force
Motion in a circular due to a force perpendicular to the motion
What does the stability of an object depend on
It’s centre of gravity
Moment of a force
Def + eg.
Measure of the force’s turning effect
-opening and closing a door along a fixed hinge
-seesaw
-unscrewing a nut with a spanner
How can energy be stored (7)
Elastic (strain)
Kinetic
Gravitational potential
Chemical potential
Electrostatic
Internal (thermal)
Nuclear
How is energy released from the sun
From nuclear fusion in the sun
Briefly how does a generator work
When a generator turns, it generates a current. This is because the turning of the generator causes a magnet to move in an electric field. This is what causes the induction of current.
How is energy obtained from wind
In wind turbines, the wind causes the generator to turn. Here, kinetic energy is converted to electrical energy.
How energy can be obtained from water (3)
Hydroelectric dams
Energy stored in Tides
Energy stored in Waves
How can energy be obtained from hydroelectric dams
water is held behind a dam, forming an artificial lake or reservoir. The force of the water being released through the dam spins the blades of a giant turbine, which turns the generator. Potential energy is converted to kinetic energy, then to electrical energy.
How can energy be obtained from waves
Waves force the water to move up and down inside the chamber, which in turn forces the air in the chamber back and forth through the turbine. This causes the turbine to turn, and thus the turbine turns the generator. Kinetic energy from the waves is turned into electrical.
How is energy obtained from tides
Tidal fence
Long row of vertical axis turbines (like wind turbines), that span across a channel or a long straight. The water is forced through the turbines, turning them. This turns the generator, which produces electrical energy. Kinetic energy is transferred into electrical energy
Sources of energy (7)
Geothermal
Nuclear
Light from the sun
Electromagnetic waves from the sun
Water
Chemical energy in Fossil fuels
Chemical energy in biofuels
Ow energy is obtained from fossil fuels
Fuels are burnt, producing a lot of heat energy, which heats a reservoir of water. This produces steam, which expands against the blades of the turbine, causing it to turn. This turns the generator, and electricity is produced. chemical energy is converted to heat energy, to kinetic/ mechanical energy, to electric energy.
How energy is obtained from geothermal sources
heat is used to heat water, which creates steam, which turns a turbine, which turns a generator. Heat energy is converted to kinetic energy, which is converted to electric energy.
How is energy obtained from nuclear sources
Source of heat energy comes from the radioactive decay of uranium that is used to boil water in a boiler. The high pressure, high temperature steam produced is used to turn a turbine, which in turn rotates a generator producing AC electricity which is feed into the national grid
How is useful energy obtained from the sun light
The sun releases light and heat in a process called nuclear fusion. The light can be used in photovoltaic cells to generate electricity and the heat energy can be used to heat water in a solar geyser.
Describe how Infrared waves from the Sun heat water
Solar panels
Water is stored in a water tank and pumped through small pipes running through the solar panel
Infrared radiation from the Sun heats the water in the pipes as it flows through them
The water returns to the tank at a higher temperature
How is wind caused
Wind is caused by uneven heating of the earth’s surface by the sun. Because the earth’s surface is made up of different types of land and water, the earth absorbs the sun’s heat at different rates.
Advantages of fossil fuels (5)
Cheap
Low-tech equipment required
Easy to transport
In abundant supply
Reliable
Fossil fuels disadvantages (2)
Harmful wastes – greenhouses gases, pollutant gases, radiation
Is non-renewable, so will run out at our current rate of consumption
Hydroelectric dam advantages (4)
No pollution
No greenhouse gases
Is a renewable resource
Reasonably reliable
Hydroelectric dam disadvantages (3)
Expensive
Must be built on bodies of water – can’t be built anywhere
May not be able to be used during periods of drought, when water levels run low
Wave energy advantages (2)
No greenhouse gases
No pollution
Wave energy disadvantages (2)
Difficult to build, so can’t be used very large scale
Not reliable – there aren’t always waves.
Geothermal advantages (4)
No greenhouse gases
A reliable resource
Renewable resource
Only cost is the maintenance
Geothermal disadvantages (2)
Deep drilling is expensive and difficult
Limited sites where it can go
Nuclear fission advantages (4)
Very reliable
Low running costs
Plants can be placed anywhere but preferably by a water source
Negligible environmental impact
Nuclear fission disadvantages (3)
Non renewable
Unsafe as accidents could lead to loss of loves and make an area uninhabitable for many years
Decommissioning of a plant is very expensive as legacy radioactive waste is very hard to get rid of
Solar energy advantages (4)
Renewable
Affordable
Can be scaled easily and put on everyone’s house
Does not produce any greenhouse gases
Solar energy disadvantage
Not reliable
Wind energy advantages (5)
Predictable
Renewable
Running costs are relatively low
Easy to scale
Does. It produce greenhouse gases
Wind energy disadvantages (3)
Initial cost can be high
Alternative power sources are needed when wind isn’t strong enough
Birds could strike the turbine blades and the noise could be a nuisance
How is energy transferred (4)
Forces (mechanical work done)
Electrical currents (electrical work done)
Heating
Electromagnetic, sound and other waves
