energy Flashcards
(21 cards)
what is a renewable energy source?
it is a energy source that can be naturally replenished faster than it is consumed
examples:wind, solar and hydroelectric
what is a non-renewable energy source?
it is a natural resource that cannot be replenished at a rate comparable to its use
example:coal, oil and gas (fossil fuels)
what is the equation for efficiency?
dividing the useful power output/total power input x 100 to express it as a percentage
what is kinetic energy?
it is the energy stored in moving objects
stationary cars have no kinetic energy
the energy stores in a car:
petrol-chemical energy store-kinetic energy store
how to convert joules into kilojoules
divide by 1000
what is elastic potential energy?
is the energy stored when an object is stretched or compressed
what is the energy changes involved when an object is projected upwards?
its kinetic energy is transformed into gravitational potential energy
how does using lubricants reduce unwanted energy transfers?
by minimising friction between moving parts when in turn energy is dissipated as heat-allows moving objects to slide more smoothly
what does dissipation mean?
the loss of energy within a system due to processes like friction or resistance resulting in energy being converted into less useful form such as heat and sound
thermal conductivity
the higher the thermal conductivity of a material the higher the rate of energy transfer by conduction through the material
what happened to energy during the Industrial Revolution?
fossil fuels become an important source of energy as it was easy to mine and provided a lot of energy
what is a system
an object or a group of objects
what does an increase in GPE indicate?
the object is higher of the ground
what happens to energy in poorly insulated windows?
heat is lost through the windows and walls
explain how using step up transformers makes the network efficient 3 marks
potential difference increased current decreases so energy losses in the transmission cables decreases
what do you always convert minutes to when calculating
seconds
what is a zero error
equipment not to do with the person
why is the step down transformers used?
decreases the voltage to a safe level for homes and businesses
factors affecting the cooling of buildings
a building with a large surface area loses heat faster
material with a low thermal conductivity reduce cooling for example wood and insulation foam
thicker walls or roofs slow down heat transfer
specific heat capacity required practical
1.place a beaker on balance and press zero
2.now add the oil to the beaker and record the mass the oil
3.place an thermometer and immersion heater into the oil
4.record the starting temperature of oil
5.wrap insulation to reduce heat loss
6.connect a joulemeter to the immersion heater
7.leave for thirty minutes
8.read the number of joules of energy that passed the immersion heater
9.read the final temperature of oil
10. calculate the specific heat capacity
