Energy Stores And Processes Flashcards
(22 cards)
What are the 7 energy stores?
- thermal
- kinetic (KE)
- gravitational (GPE)
- chemical
- elastic
- nuclear
- electrical
What are the 4 ways of transferring energy?
- heating (e.g. conduction)
- waves (e.g. sound)
- electric current
- force (e.g. friction)
What is a system?
A system is an object/group of objects in which electricity is transferred between them.
What is work done?
Energy transferred
What are the two main types of work done?
Heating - energy stored thermally
Mechanical - work done against a force
What are the units for work done?
Joules - same as energy
What equation links work done, force and distance?
Work done = force x distance
W = F x s or Fs
What is the equation to find kinetic energy?
Kinetic energy = mass x velocity squared / 2
Ek = mv^2 / 2
What is kinetic energy?
Kinetic energy can be described as the movement of an object/objects
What is gravitational potential energy (GPE)?
Energy is in the gravitational potential store when an object moves in relation to its position in a gravitational field
How do we calculate GPE?
Work done = mass x gravitational field strength
W = mg
How do we calculate a change in the GPE store?
GPE = mass x gravitational field strength x (change in) height Ep = mgh
What is the law of conservation of energy?
Energy can never be created or destroyed, only transferred usefully or dissipated to the surroundings
How are GPE and KE linked?
GPE lost = KE gained. In other words, when an object falls it has less GPE but gains KE as it falls
What is specific heat capacity (SHC)?
SHC (measured in J/kg *C) is the amount of energy required to heat 1 kilogram of a given substance by one degree Celsius. Unless otherwise stated, ignore the energy that is lost through dissipation
What is power?
Power is defined as the rate at which energy is transferred or the rate at which work is done
What equation links power, work done and time?
Power = work done / time taken P = E / t
What is the equation for efficiency?
Efficiency = useful output energy/total output energy
There is no symbol equation for efficiency
What is elasticity and plasticity?
Elasticity is identifiable by an ability to return to its original shape after deformation
Plasticity is identifiable by a (somewhat) inability to return to its original shape.
What is Hooke’s Law?
The extension of an elastic object (e.g. spring) is directly proportional to the force applied, provided the limit of proportionality is not exceeded
What equation links force, spring constant and extension?
Force applied = sprint constant x extension
How do we calculate the elastic potential energy store?
EPE = 1/2 x spring constant x extension squared Ee = ke^2 / 2
