P1 Flashcards
Explain the changes of energy stores when an object is being projected upwards
The person exerts a force onto the ball to project it upwards, they transfer the chemical energy store to the ball which becomes kinetic energy as it moves up, the ball also gains GPE.
When the ball comes back down, the GPE turns into kinetic energy
Energy changes when a car is slowing down
Friction acts between the wheels and the brakes to slow the car down, the kinetic energy stores in the wheels turn into thermal energy stores to the surroundings.
Energy changes when a car is hitting a wall
The kinetic energy stores turns into many different energy stores, some of it becomes EPE, some becomes thermal energy stores and some turns into sound waves
energy changes when bringing water to a boil in an electric kettle
the electrical energy is transferred to the thermal energy store, energy is transferred to the waters thermal energy store by heating therefore the temperature of the water increases
what is the limit of proportionality
when a spring is elastically deformed and cannot return to its normal state. Normally, the higher the force, the higher the spring extension in cm but once it exceeds the limit of proportionality then that rule no longer applies
What is power
the rate of energy transfer
Powerful machines
If there are two cars which are completely the same apart from the power that is inside their engines. If both cars race the same distance, the car with the more powerful engine will reach the finish line faster because it is producing the same amount of energy in the same amount of time
Power in electrical appliances
The total energy of an appliance depends on how long its on for and its power.
the power is the amount of energy transfers per second
the more energy transfers in a given time, means higher power.
Appliances are often given power ratings that will tell you the amount of energy transfers per second, an appliance with a higher power will be more expensive due to the higher amount of energy transfers per second, e.g 600W and 850W
the national grid’s job
the national grid is a giant system of cables and transformers that transfer electrical power to power stations to consumers in the UK.
Electricity production meeting demand
The amount of electricity demand changes throughout the day, people use more when they wake up, come home from school and work and when its night. The amount of power produced is to meet these changes. Power stations normally work well below their power maximum output meaning that they can deal with unexpected power station shutdowns and cope with high demand
Transfer of energy through cables
high power is needed to meet the high amounts of energy produced by the national grid. To do this the potential difference or the current must be very high. if the current is too high there will be wasted energy when the current heats up the cables, which makes the national grid less efficient. So the step up transformer increases the potential difference from power stations to electric cables, the step down transformers brings the pd back down to safe levels before being sent into homes
density
the more tightly packed the particles are the higher the density of the object. This means that solids and liquids are normally much more dense than gases. solids are the most dense and then liquids and then gases
particle motion within gases
At higher temperatures, the particles within a container will have more collisions per second with the walls of the container, this is due to the higher temp causing it to have a higher kinetic energy and the more particle collisions per second means a higher pressure
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