3) Conservation of Energy Flashcards
What are the stores of energy?
Kinetic Gravitational potential energy Chemical Thermal Elastic potential energy Nuclear
What is the internal store?
Kinetic energy stored in particles + chemical energy stored in chemical bonds between particles
How is energy added to the body?
Eating food
What property of an object is a measure of the energy stored in the kinetic stores of its particles?
Temperature
What is kinetic energy measured in?
Joules (J)
What is the equation for kinetic energy?
KE = 0.5 x m x v^2
What is the equation for GPE?
GPE = m x g x h
What is the equation for elastic potential energy?
elastic potential energy = 0.5 x spring constant x extension^2
EE = 0/5 x k x e^2
How can energy be transferred between stores?
Heating
Mechanical work
Electrical work
Waves
How is more work done?
Push with equal force for longer distance
Push with larger force for same distance
What is the equation for work done?
Work done = force x distance
What is the equation for electrical energy?
Electrical energy = power x time
E = V x I x t
What is the work done by a force equal to?
The energy transferred to the object
What is the equation for efficiency?
Efficiency = (useful power output / total power output) x 100
What is the unit for power?
Watts (W)
What are the ways to reduce unwanted energy transfer?
Thermal insulation
Lubrication
How is heat loss reduced in homes?
Fit loft insulation
Use double glazing
Use cavity wall insulation
Fit carpets
How does wall size affect insulation?
Thicker walls = less heat lost
Lower thermal conductivity material = less heat lost
How does lubrication reduce heat loss?
Reduces frictional forces
What is an energy resource?
A resource used to generate electricity and other forms of energy
What are the stages of collecting energy from a turbine?
1) Energy resource is used to rotate a turbine
2) Rotating turbine rotates a coil of wire in a magnetic field (a generator)
3) Coil of wire creates an electric current
What are advantages of fossil fuels?
Reliable
On demand electricity
How is energy created from fossil fuels?
Fossil fuels are burnt to heat a fluid which creates steam and turns a turbine
What are disadvantages of fossil fuels?
Not renewable
Inefficient
Contributes to global warming
What is geothermal energy?
Natural energy by heating
Volcanoes, magma
What are advantges of geothermal energy?
Nenewable
Reliable
What are disadvantages of geothermal energy?
Can only be used where volcanic activity is close to the surface
What are advantages of wind power?
Renewable energy
What are disadvantages of wind power?
Unreliable, needs blowing wind
What are advantages of hydroelectric power?
Renewable
More reliable than wind and solar
What are disadvantages of hydroelectric power?
Hydroelectic dams change the paths of rivers
What are advantages of tidal energy?
Renewable source of energy
What are disadvantages of tidal energy?
Creation of tidal turbines can damage ecosystems
How does hydroelectric power work?
Dams trap high water and when dropped it rotates a turbine
What are advantages of nuclear energy?
No greenhouse gas emission
Reliable
What are disadvantages of nuclear energy?
Disposal of long half-life waste can cause safety issues
Long term damage if an accident occurs
How does nuclear energy work?
Nuclear energy stored in nuclei is relseased and heats up graphite creating water and steam
What are advantages of solar enegry?
Renewable
What are disadvanatges of solar energy?
Only produces electricity when there is sunlight
What is the orignal source of energy?
The sun
What are the energy resources?
Geothermal Tidal Wind Water Solar Nuclear Fossil fuels
What are some uses of energy sources?
Transport
Heating
When did electricity use begin to decline in the UK?
21st century
Why has the use of enegry resources changed over time?
Technological advances
Environmental concerns
Changing costs
How are we solving the energy problem?
Electric vehicles
Government policies
Renewable power plants
What are limits to renewable energy sources?
Politics
Cost
Reliability