ch5 - work, energy and power Flashcards
(27 cards)
‘doing work’
way of transferring energy from on object to another
‘doing work’
way of transferring energy from on object to another
doing work ON something =
transferring energy TO the thing
what is energy?
a calculated quantity that is conserved during any change, that which is transferred when a force does work
more work done =
. more force
. more distance
what is work done?
when a force displaces the body in the direction of the force, energy is transferred
work done formula
force * distance in the direction if the force
work done = energy transferred
work done component formula?
w = Fs cos O
what is gravitational potential energy?
the energy a body has due ti its position in a gravitational field
gpe formula
gpe = mgh
gpe = mgh derivation
energy transferred = work done
gpe = F * s
gpe = weight * h
gpe = mg * h
gpe = mgh
potential energy?
energy of an object because of its position or shape
forms of potential energy?
. gravitational - object in gravitational field
. electric - electrically charged of bject in an electrical field
. elastic - of a squashed, twisted, stretched objsct goes back to its original position
kinetic energy formula?
0.5mv²
ke formula derivation?
v² = 2as + 0
times both sides by 0.5m
0.5mv² = mas
0.5mv² = Fs
energy transferred = work done
more ke
more speed of motion of force
gpe and ke on a hill?
- top of hill, max gpe
- going downhill, gpe to ke
- bottom of hill, all gpe to ke, sound, heat
- going uphill, ke to gpe
percentage efficiency?
useful output / total input * 100%
sankey diagram
to show energy transfers
principle of conservation of energy
energy cannot be created or destroyed - only changed from one form to another
total energy before = total energy aft r
power?
rate at with the device does work per unit time
power formula
P = W/t
P = Fv
