P1- Conservation And Dissipation Of Energy Flashcards
What is energy?
The capacity of something to do work.
What happens if something contains a story of energy?
It is able to do work.
What is the law of conservation of energy?
‘Energy cannot be created or destroyed only stored or transferred.’
What is kinetic energy?
The energy of a moving object.
What is gravitational energy?
The energy something gains when you lift it up and which it loses when it falls.
What is elastic energy?
The energy of a stretched spring or electric band.
What is magnetic energy?
The energy due to the force of attraction (or repulsion) between two charges
What is electrostatic energy?
The energy due to their e of attraction (or repulsion) between two charges.
What is chemical energy?
The energy contained in a chemical substance.
What is nuclear energy?
The energy contained within the nucleus of an atom.
What is thermal energy?
The energy something has due to its temp or state.
What is mechanical energy transfer?
When a force acts on a body energy can be transferred between two stores.
What is electrical energy transfer?
Electricity can transfer energy from a power source delivering it to components within a circuit.
What is a heat energy transfer?
Thermal energy can be transferred from place to place by the processes of conduction convection and thermal radiation.
What is radiation energy transfer?
Light and sound carry energy and so can transfer between places.
What one thing is pointed out from the law of conservation of energy?
A close system (a region a group of objects from which nothing can enter or escape) the total amount of energy is constant.
What energy transfer would occur from a moving object hitting an obstacle? For example a car hitting a brick wall…
The kinetic energy store would transfer to a thermal energy store
Two points about kinetic energy:
- It is the energy result of its speed.
- Energy an object has when it’s moving
What is the equation for kinetic energy?
Kinetic energy = 1/2 x mass x speed²
KE = 1/2 x m x v²
Two points about gravitational potential energy:
- it is the energy it has due to its height in a gravitational field.
- if an object is lifted up it will gain GPE
What is the equation for gravitational potential energy?
Gravitational potential energy = mass x gravitational field strength x height
GPE = m x g(gfs) x h
Two points about elastic potential energy:
- When is spring is stretched or compressed work is done on the spring which will result in a transfer of energy to the spring’s elastic store.
- The work done on the spring is equal to the amount of energy stored.
What is the equation for elastic potential energy?
Energy = 0.5 x spring constant x extension²
E = 1/2 k x²
‘A gas cooker, heating a pan of water, takes energy from the ______store of the gas and transfers it to the ______ store of the water’
Fill in the blanks:
- Chemical
2. Thermal
What forms of energy have a tendency to spread out (dissipate)?
Heat, light and sound energy
What three disadvantages are there to dissipation of energy?
- becomes very difficult to gather the energy back together again.
- results in energy becoming less useful
- whenever a process produces unwanted heat, light or sound Energy that ends up in those forms is essentially wasted.
In which two ways can energy loss be reduced?
- Reducing the amount of unwonted energy that is produced.
- Preventing energy from dissipating.
How can you prevent wanted heat from dissipating less heat?
Insulators:
- how will the installation conduct heat
- How thick the installation is
What usually happens whenever energy transferred from one form to another? And what energy forms does it usually turn in to?
Some of that energy is usually wasted and ends up in the form of heat, light or sound.
What is the efficiency of a system?
The proportion of energy that ends up in the intended form.
What is the equation for efficiency?
Useful energy transferred by device
Efficiency = ————————————————————
Total energy supplied to the device
What number is efficiency usually given as?
A number between 0 to 1 but it can occasionally be given as a percentage.
For example 40% of efficiency is the same as the efficiency of 0.4 and 1 efficiency is the same as 100% efficient.
