P1 Flashcards
What are the 8 energy stores you need to know?
Thermal Chemical
Kinetic Magnetic
Grav Po Electrostatic
Elastic Po Nuclear
How is energy transferred? (4 ways)
Mechanically (by a force doing work)
Electrically (work done by moving charges)
By heating or by radiation
Explain how when a system ( a single or group of objects) changes, energy is transferred?
When a system changes, energy is transferred.
It can be transferred into or away from the system.
or between different objects in the system
or between different types of stores.
What is a closed system?
Where neither matter nor energy can enter or leave.
Net change in total energy is always zero
Explain how energy can be transferred by heating? (Example: kettle boiling water)
The water is the system.
Energy is transferred to the water (from kettles heating element) by heating, into the waters thermal energy store (temp rises therefore).
What is work done?
Work done is another way of sauing energy transferred
When a system changes, energy is transferred by doing work. When is work done?
Work can be done when current flows (work is done against resistance in a circuit) or by a force moving an object)
Examples of work being done (Person throwing a ball, friction of cars brakes and wheels, collision between two cars)
–The Initial force exerted by person to through a ball upwards does work. Causes an energy transfer from chemical of persons arm to kinetic store of ball and arm.
–Friction between a car’s brakes and its wheels does work as it slows down. Causes energy transfer from wheels kinetic store to thermal store of surroundings.
– In Collision between car and stationary object, normal contact force between car + object does work. Causes energy transferred from car’s kinetic store to other energy stores. (Thermal stores of car and object)
Kinetic energy: Fact File
::: Anything moving has energy in its kinetic energy store
::: Energy transfers to this store when objects speed up and is transferred away when slows down
::: Energy in kinetic energy store depends on objects mass and speed
::: The greater the mass, the faster its going, the more emergy there will be in its kinetic energy store.
Grav Potential Energy store: Fact File
::: lifting an object in grav field requires work
::: Causes transfer of energy to the G.P.E of the raised object ( higher it is, more energy transferred)
::: amount of energy in g.p.e store depends on mass, height, stength of grav field
How do falling objects transfer energy?
When an object falls, energy is transferred from the G.P.E store to the kinetic energy store.
When theres no air resistance:
ENERGY LOST FROM G.P.E STORE = ENERGY GAINED IN THE KINETIC ENERGY STORE
( air resistance acts against falling objects so some energy is transferred to other stores.)
How does stretching transfer energy to the elastic potential energy store?
Stretching an object transfers energy to its elastic potential energy store so long as the limit of proportionality has not been exceeded
What is the conservation of energy principle?
Energy can be transferred usefully, stored or dissipated, but can never be created or destroyed.
What is useful energy and wasted energy?
Useful energy is energy transferred to ehere it is wanted in the way that is wanted but WASTED energy is energy that is not usefully transferred.
What is dissipated energy.
Dissipated energy is basically wasted energy as it is being stored in a not useful way.
