Work, Energy, Power Flashcards
Work Energy Conversion and Conservation Efficiency Potential Energy and Kinetic Energy Power
Work done by a force F on a body
product of that force and the displacement of the body in the direction of the force
Wby f = Fscosθ
θ angle between F and s
Work done J
Work done by a force F on a body
product of that force and the displacement of the body in the direction of the force
Wby f = Fscosθ
θ angle between F and s
Work done [J]
Joule
work done by a force of 1 newton when its point of app moves through a displacement of 1 metre in the direction of the force
work done
W = area under F-s graph
Work done by gas
W = pΔV
p external pressure [Pa]
ΔV change in volume of gas [m³]
kinetic energy
Ek= 1/2 m v²
Work-Energy theorem
The work done on a rigid body by the resultant force is always equal to the change in kinetic energy of the body
Wby f =ΔEk
Potential energy Ep
Ep =mgh
Principle of Conservation of Energy
The total energy of an isolated system is constant. Energy cannot be created or destroyed but may be transformed from one form to another
KE intial + PE initial + E supplied = KE final + PE final + E dissipative forces
Power
rate of work done or energy transfer
unit W or J s-¹
P = δW/δt
= δ (Fs)/δt
=F (δs/δt)
= Fv
efficiency η
η = useful energy(power) output/ energy(power) input ×100%
