3: Energy - YK Flashcards
(18 cards)
What are the formulas for work and power?
work (in J) = force * distance
power (in W) = work done / time taken = force * speed
What is work done, energy, and power?
Work done is the same as energy transferred, energy is the ability to do work, power is the work done in a unit of time
What are the types of energy?
Kinetic Energy; Gravitational Potential Energy; Elastic Potential Energy; Internal Energy (Heat); Sound Energy; Electrical Energy; Magnetic Energy; Chemical Energy; Nuclear Energy
What are the formulas for gravitational potential energy and kinetic energy?
GPE = mass * acceleration from gravity * height (= mgh) KE = 1/2 * mass * velocity^2 = (1/2)m(v^2)
What is the law of conservation of energy?
Energy cannot be created or destroyed, it can only be converted from one form to another (energy before = energy after)
What is the formula for energy efficiency?
useful energy output / total energy output ( * 100 for percentage)
What are renewable and non-renewable sources of energy?
A non-renewable resource of energy is one which cannot be replaced easily (will eventually
run out); a renewable resource of energy is one which can be replaced easily (don’t release pollution or greenhouse gases)
What are the fossil fuels?
Coal, natural gas, and oil. They are efficient and reliable sources of energy but they pollute the atmosphere and release greenhouse gases. Nuclear energy (not a fossil fuel) doesn’t release pollution or greenhouse gases but creates radioactive waste.
What does heating and cooling an object do?
Objects expand when heated and contract when cooled, gases expand more than liquids expand more than solids
What is heat and and how can it be transferred?
Heat is the transfer of energy between two objects, it can be transferred by conduction, convection, radiation, and evaporation
What is conduction?
The transfer of energy by the vibration of particles (between two adjacent surfaces)
What is convection?
The transfer of energy due to convection currents (hot fluids rising and cold fluids falling)
What is thermal radiation?
The movement of energy from place to place by electromagnetic waves
What is the order of waves in the EM spectrum (increasing energy and frequency, decreasing wavelength)?
Radio Waves; Microwaves; Infra-red; Visible light (ROYGBIV); Ultraviolet; X-rays; Gamma Rays
How does type of surface affect radiation emmission/absorption?
Dull black surfaces are better at emitting/radiating energy and absorbing radiation, bright shiny surfaces are poor emitters and absorbers of radiation
What is evaporation?
The liberation of particles from the surface of a fluid due to collisions within the fluid (evaporation only happens at the surface of the fluid but at all temperatures, boiling happens everywhere but only at boiling point)
What does particle theory say about the states of matter?
Solids: particles are close together and constantly vibrating around a fixed position (faster when hotter)
Liquids: particles close together but in constant random motion, heat makes particles move faster and collide more with each other and container (increase of rate and energy of collisions increases pressure and evaporation)
Gases: particles far apart and in constant random motion in straight lines until they hit something, gases expand to fill all available space in a container, constant collisions, heat increases rate and energy of collisions so pressure and evaporation
What does a power station do?
Use energy from combustion/nuclear reactions to boil water, producing steam which a turbine and generator (converting KE to electrical energy)
