10 Work,energy and power Flashcards
energy
the capacity to do work
principle of conservation energy
energy can’t be created or destroyed
work
force x distance moved in the direction of the force
potential energy
the energy of an object due to its position
∆Ep = mg∆h
power
rate of transfer of energy
P=∆E / ∆t
P= ∆W / ∆t
load
the force to be overcome by a machine when it shifts or raises an object
effort
the force applied to a machine to make it move
useful energy
energy transferred to where it is wanted when it is wanted
work done
force x distance moved in the direction of the force
force and displacement
energy transferred
W = Fs Cos
force-displacement
area under the line response the work done
force-distance graph
area under the line respects total work done
hooke’s law
the extension of a spring is proportional to the force applied to it
stretch of the spring extension of ∆L
W=1/2 F∆L
kinetic energy
energy of an object due to its motion
Ek = 1/2 mv^2
engine power
P = Fv
motive power
energy per second wasted due to restive forces + gain of kinetic energy
out power
Pout = Fv
Work done equation
W= Fs
efficiency of a machine
useful energy transferred by the machine / energy supplied to the machine
useful output power / input power
rate of doing work = rate of energy transfer
P = ΔW / Δt = Fv
