chapter 5 - work energy power Flashcards
work done =
Force x distance traveled in the direction of the force = Fs
= energy transferred
Nm or J = kgm^2s^-2
- have to use the component of the force parallel to the direction of movement of the distance parallel to the force
work done at an angle
= Fs cosθ
where θ is the angle between the force and motion
energy
the capacity of one object/ system to do work
J
= work done
perpetual motion
a device in which once started will continue to move and do work without any further input of energy
this is impossible according the principle of conservation of energy
area under force distance graph
work done
principle of conservation of energy
the energy in a closed system always remains constant
energy can never be created or destroyed only transferred
forms of energy (9)
- kinetic
- GPE
- chemical
- elastic potential
- electrical potential
- nuclear
- radiant
- sound
- thermal
kinetic energy
- due to motion
= 1/2mv^2
GPE
due to the position of a mass in a UNIFORM graviattional field
= mgh
chemical
energy due to bonds between atoms in a substance
elastic potential
due to a reversible change in shape of an object
E = 1/2 Fx
electrical potential
due to the position of charge in an electrical field
nuclear
due to forces between protons and neutrons in an atom
radiant
energy due to EM waves
sound
energy due to mecgnaical wave motion of atoms
thermal
energy due to randomly distributed potential and kinetic energies of atoms within a system
KE is proportional to
v^2
m
energy exchange (KE and GPE)
mgh = 1/2 mv^2
v = root(2gh)
effect of friction on a moving object
transfers KE to thermal energy
power
rate of work done or energy transfered
= WD/t = Fv
Watts or J/s or kgm^2s^-3
efficiency
useful energy output/ total energy input *100
