P1- Energy Flashcards
Outline the four types of energy transfer
Mechanical (by a force doing work), Electrically (work done by moving charges), Heating or Radiation (eg light or sound)
List the 8 types of Energy stores
Thermal, Kinetic, Gravitational P, Elastic P, Chemical, Magnetic, Electrostatic, Nuclear
Energy is never….?
Used up
Energy is not used up it is….?
Transferred between different objects and energy stores.
Where does energy go once it is transferred?
One of the objects energy stores
What is a system?
a single or group of objects
In a system, where can energy be transferred to?
into or away
between different objects in system or different energy stores
What is a closed system?
a system where neither matter nor energy can enter or leave
What is the net change in total energy of a system?
0
Define “work done”
Energy transferred
When can “work be done”
When current flows or by a force moving on an object
Equation for kinetic energy
Ek=1/2mv²
KE = 1/2 x mass x speed²
Joules = 1/2 x kg x m/s
When is energy transferred to and from the kinetic energy store?
To the store when an object speeds up
Away from it when the object slows down
What is kinetic energy?
Energy due to an object being in motion
When is energy transferred to gravitational potential energy stores?
If an object in a gravitational field is lifted, work is done and there is a transfer of energy to the store of the raised object.
When is more energy transferred to a GPE store?
If an object is lifted higher
Amount of energy in a kinetic store depends on….
Mass and speed
Amount of energy in a GPE store depends on….
Mass and height of the object
Strength of gravitational field
Equation for Gravitational Potential Energy
Ep = mgh
GPE = mass x GFS x height
Joules = kg x n/kg x m
Where is energy transferred when an object falls?
From its GPE store to its kinetic energy store
Where is energy from stretching or squashing transferred?
Elastic Potential Energy Store
Does the formula for EPE work after the limit of proportionality has been exceeded?
No
Define limit of proportionality
The point where the spring can no longer stretch and Hooke’s law is no longer true
Equation for EPE of a stretched spring
Ee = 1/2ke²
EPE=1/2xspring constantx extension²
Joules = 1/2 x n/m x m
What is Hooke’s law?
The strain in a solid is proportional to the applied stress within the elastic limit of that solid.
Define specific heat capacity?
The thermal energy required to raise the temperature of a substance
Equation that links energy transferred to specific heat capacity
△E = mc△θ
Change in thermal energy = mass x specific heat capacity X temperature change
Joules = kg X j/kg°C x°C
What is the conservation of energy principle
Energy can be transferred usefully, stored, dissipated but never created or destroyed
What happens to non useful energy transferred?
It is dissipated energy or wasted energy
Example of energy transfer (phone)
When using a phone, energy is transferred usefully from the chemical energy store of the battery in your phone.
Some energy is dissipated into the phones thermal energy store causing the phone to warm up.
Example of energy transfer (flasks and closed systems)
A cold spoon is dropped into an insulated flask of hot soup which is then sealed.
if the flask is a perfect thermal insulator the spoon and soup form a closed system.
Energy is transferred from the thermal energy store of the soup to the useless thermal energy store of the spoon. No energy has left the system.
What is power?
The rate of energy transfer or rate of doing work
What is power measured in?
Watts
