paper 1 Flashcards
kinetic energy equation
Ek(J) = 0.5 x mass(kg) x speed (m/s)^2
kinetic energy
the energy stored in moving objects
stationary objects have no kinetic energy
Example: driving a car
chemical energy stored in petrol –> kinetic energy store of the moving car.
question: a car with the mass of 700 kg is moving with a speed of 20m/s. Calculate the kinetic energy of the car
EK= 0.5 x m(kg) x v^2
Ek= 0.5 x 700 x 20^2
Ek = 1400,000 j
Ek = 140 kj
kinetic energy triangle
. kinetic energy
1/2 Mass (kg) Speed (m/s)
elastic potential energy
energy stored as a result of applying a force to deform an elastic object.
elastic potential energy explanation
when we stretch a spring we’re applying a FORCE to change the LENGTH of the spring.
applying a force like this is called doing “WORK”
we’re putting ENERGY in to stretch the spring. the stretched spring is string .
The stretched spring is strong this energy and we call that energy ELASTIC POTENTIAL ENERGY
extension
the amount of force(n) that is acting upon the spring this is given in the symbol (e)
directly proportional to the force but there is a limit of proportionality and will not return to its original length if the force is removed
elastic potential energy equation
Ee = 0.5 x k x e^2
EPE (J) spring constant (n/M) extension
formula triangle
. EPE
1/2 spring constant (K) extension (e^2)
gravitational potential energy
is the energy stored in an object due to its position above the earth’s surface. due to the force of gravity
gravitational potential energy
Ep = mass (kg) x gravitational field strength (N/kg) x height(m)
specific heat capacity
the amount of energy required to raise the temperature of 1kg of the substance by 1 degrees
specific heat capacity
change in T energy (J) = mass(kg) x specific heat capacity (J/kg) x change in tem(c)
specific heat capacity formula triangle
. change in energy
mass (kg) specific heat capacity change in temp (C)
the law of conservation of energy
energy can transferred usefully, stored or dissipated but cannot be created or destroyed
system
a group of objects
closed system
no energy can enter or leave
pendulum system
top of the swing is the max GPE and it is transferred to the kinetic energy store at the bottom the mass experiences the maximum KE of the mass and that kinetic energy is transferred again to GPE
the thermal energy created by friction is wasted and is being dissipated which will cause the pendulum to swing and eventually stop.
bungee jump system
- gravitational potential energy in the store of the jumper
- as the jumper jumps the gravitational potential energy is transferred to kinetic energy
- when the bunge is just about to tighten that’s when the kinetic energy is the most
- then when the rope is fully extended there is no longer any kinetic energy
- then all the energy is transferred to the elastic energy store
the jumper never returns back to it original position as the thermal energy is dissipated via friction with air particles.
work
work is done whenever energy is transferred from one store to another
mechanical work
involves using a force to move an object
electrical work involves
a current transferring energy
work done example: dog pulling a sled
chemical store in the dog ——-> transferred to the kinetic energy store in the moving sledge ———-> thermal energy stores in he sled and into the ground
the dog is using a force of 50N and the sled is moving 3 metres
work done equation
work done (J) + Force (N) x Distance (M)
power
the rate at which energy is transferred or the rate at which work is done
power equation (energy transferred )
. energy transferred (J)
power (W) = ———————————–
. time (s)
power equation ( work done )
. work done (J)
power (W) = ————————————–
. time (S)
what is a watt
1 watt (W) is an energy transfer ( or work done of 1 (J) per second
efficiency equation ( energy transfer )
. useful output energy transfer
efficiency = ——————————————-
. total input energy transfers
efficiency equation ( power)
. useful power output
efficiency = ————————————————–
. total power
thermal conductivity
the unit of the rate of energy transfer by conductivity across that material
specific heat capacity
the amount of energy required to raise the temperature of 1kg by 1c
specific heat capacity required practical
- place beaker on a balance and press zero
- place 1 kg of oil in the beaker
- put an immersion heater and a thermometer in the oil
- read and record the starting temp of the oil.
- wrap the beaker in insulating foam
- attach A joulemeter and a power pack to the immersion heater
- leave for 30 minutes
- read the total number of joules that passed into the immersion heater and the final temp
- use equation to calculate the specific heat capacity
sources of inaccuracy
- thermal energy leaking out of the beaker - to prevent this make sure your wrap in an insulator with a low thermal conductivity.
- not all thermal energy is passing into the oil - ensure the immersion heater is fully submerged
- incorrectly reading the thermometer - use an electronic temperature probe
- thermal energy might not be spread through the oil - stir the oil
fosil fuel advantages
- fossil fuels are reliable they always provide energy when we need it
- they release lots of energy
- they are abundant and are relatively cheap
- they are very versatile, they can be used for heating, factories, and transport.
fosil fuel disadvantages
- burning fossil fuels release a huge amount of co2
- fossil fuels are nonrenewable so they are not being replaced as we use them so they will run out
- they can release other pollutants such as nitrogen oxides and sulfur dioxide
4.
nuclear power
nuclear power is non-renewable as it runs on the elements uranium and plutonium
nuclear power adv
- does not release carbon dioxide
- it is extremely reliable it generates a lot of electricity exactly when we want it
nuclear power dis adv
- they contain highly dangerous radioactive materials. if there’s an accident then these materials could be released into the environment
- when the power plants are done they need to be decommissioned which takes a lot of time and is extremely expensive
- at the end of the power plants life it creates large amounts of highly dangerous waste which must be stored for thousands of years before its safe.
the UKs energy stores
- the uk has an abundance of coal, which was the source of almost all the UKs power until 1950.
- nuclear power takes up about 20%of the uks electricity.
- oil and gas from the north sea began to replace coal for electricity generation
- gas generates less co2 than burning coal which contributes less to climate change.
- gas fired power stations can be turned om quickly during periods of high demand ( short startup time)
renewable energy in the uk
in 2005 the kyoto protocol committed countries to reducing greenhouse gas emissions.
the uk has one of the best positions foe wind farms in the world and has opened up a large number of wind farms over the uk wind is now 11% of uk power
one disadvantage of renewables is that they are unreliable as if there is less wind the wind turbines will generate less energy.
the future of uk energy
tio make sure that the uks energy is consistent we need a baseload which is a constant supply of electricity; nuclear power is ideal
gas fired power stations can provide emergency power in times of peak demand
renewable energy
a renewable energy source is one that is being (or can be replenished as it is used)
