Chapter 5: Work, Power, Energy Definitions Flashcards
Work done
Product of force and distance moved in direction of force
units: joules
work done= F*distance moved (x)
work done= energy transferred
Energy
The capacity to do work
units: joules
PRINCIPLE OF CONSERVATION OF ENERGY
The total energy of a closed system remains constant as energy cannot be created or destroyed. It can only be transferred from one form to another.
Kinetic Energy
The energy associated with an object as a result of its motion.
kinetic energy=0.5mv^2
(derivation)
Gravitational potential energy
The capacity for doing work as a result of an object’s position in a gravitational field
Chemical energy
energy contained within the chemical bonds between atoms it can be released when atoms are rearranged.
e.g. in a chemical cell
food
Elastic potential energy
energy stored in an object as a result of reversible change in its shape
e.g. a stretched guitar string
a squashed string
Nuclear energy
energy within the nuclei of atoms- it can be released when the particles within the nucleus are rearranged
e.g. energy from nuclear fusion in sun
sound energy
energy of mechanical waves due to the movement of atoms
e.g. energy emitted when you clap
radiant ( electromagnetic energy)
energy associated with all EM waves, stored within the oscillating electric and magnetic fields
e.g.energy from sun
thermal energy
the sum of the random potential and kinetic energies of atoms in a system
uniform gravitational field
A gravitational field in which field lines are parallel and the value for g(9.81) remains constant.
Power
the rate of work done
P=E/t
P=Fv
units: watts
Efficiency
The ratio of useful output energy to total input energy
efficiency =( useful output energy/ total input energy)*100
