Chapter 7 : Conservation of Energy
CHEE ZI QING A20SC0043
Conservative and Non conservative Forces
Potential Energy
Mechanical Energy and its Conservation
Problem Solving Using Conservation of Mechanical Energy
The Law of Conservation of Energy
Energy Conservation with Dissipative Forces: Solving Problems
Power
Gravitational Potential Energy and Escape Velocity
Potential Energy Diagrams:Stable and Unstable
conservative = object moving any closed path is zero
conservative forces : Gravitational, Elastic, and Electric
non conservative forces : Friction, Air resistance, Tension
can be transformed but cannot be destroyed or created
U=mgh (h=y2-y1) = (1/2)kx^2
when the object is droped U(potential energy) becomes K (kinetic energy)
F = -kx (hookes law about the spring compressed or stretch
E (total mechanic energy) = K + U
Mechanical energy is conserve, so the intial=final
Using the formula of E = K+U
P (Watt / Js^-1) = Force x velocity (Fv)
P = Energy / Time (E/t)
Example of nonconservative or dissipative forces is friction, heat, Electrical/ Chemical energy......
total amount of energy remains constant
Gravitational Force, F(Newton)= -GMm/R^2, negative sign indicate attractive
gravitational field strenght, g (ms^-2)= -GM/ r^2
Gravitational Potential energy, U(Joule)= -GMm/ r
Escape velocity, V = (2gR)^1/2
kinetic energy, K= GMm/ 2r
rate of work is done