Work, Energy Power Flashcards
What is work done
work done by a force is defined as the product of the force and displacement in the direction of the force
- W = Fs
What is the definition of a joule
1 joule is defined as the work done when a force of 1 newton moves its point of application by 1 meter in the direction of the force
What is represented by the area under a pressure - volume graph
work done by a gas
W = PΔV
What is the energy possessed by a system
It is the capacity of the system to do work
What is the principle of conservation of energy
It states that energy can neither by created nor destroyed in any process. It can’t be transformed from one form to another and transferred from on system to another, but the total amount remains constant
What is kinetic energy
v^2 = u^2 + 2as v^2 = u^2 + 2(F/m)s mv^2 = mu^2 + 2Fs Fs = 1/2(mv^2) - 1/2(mu^s)
If the object starts from rest, Fs = 1/2(mv^2)
KE = 1/2mv^2
What is the change in gravitational potential energy
W = Fs W = mg(h2 - h1) W = PE final - PE initial
GPE = mgh
What is the relationship between force and potential energy
F = -( dU/dx )
F is equal to the negatives of the potential energy gradient
What is power
Power is defined as work done per unit time
P = W/t
What is the definition of a watt
1 watt is defined as the power when one joule of work is done per second
What is instantaneous power?
P = dW/dt
What is the power of a object at constant velocity
P = Fv
What is efficiency
η = (Useful output energy)/(input energy) x 100% η = (Useful mechanical work done/(input energy) x 100% η = (Useful output power)/(input power) x 100%
