Topic 3: conservation of energy Flashcards
formula for change in gravitational PE
change in gravitational potential energy (J) = mass(g) x gravitational field strength(N/kg) x change in vertical height(m)
∆GPE = m× g ×∆h
formula for kinetic energy
kinetic energy(J) = 1/2 x mass(kg) x (speed)^2 ((m/s)2) KE = 1/2 x m x v^2
What is the Law Of Conservation?
The Law Of Conservation tells us that ENERGY CANNOT be created or destroyed, only transfered into another type of energy.
Elastic Potential energy formula?
Ee = 1/2 X k X e^2
8 main stores of energy
magnetic internal chemical kinetic electrostatic elastic potential gravitational potential nuclear
what are the 4 main pathways for transferring energy
mechanical work
electrical work
heating
radiation
explain the link between energy transfers in a closed system and total energy in that system
where there are energy transfers in a closed system there is no net change to the total energy in that system
when do mechanical processes become wasteful
when they cause a rise in temperature so dissipating energy in heating the surroundings
formula for efficiency
efficiency = (useful energy transferred by the device) / ( total energy supplied to the device)
what are the effects of the thickness and thermal conductivity of the walls of a building on its rate of cooling qualitatively
A building with walls of a high thermal conductivity will cool down faster than one with walls of a low thermal conductivity.
how can efficiency be increased
by reducing the wasteful dissipation of energy to the surroundings
what are the 7 main energy sources available for use on earth
fossil fuels nuclear fuels bio-fuel wind hydro-electricity the tides the sun
