Energy Power Formulae
Energy Power Formulae
The standardised acceleration due to gravity ;Mass Moment of Inertia
The mass moment of inertia of a body about an axis has been defined as the sum of the products of mass-elements and the square of their distance from the axis
Work and Power
The Work Done W (= Joules = N.m ) by constant Force F_x (N) applied for a distance x (m)
W = F_x . x
Power is the rate of doing Work P (= Watts = N.m / s ) by constant Force F_x (N) applied for a distance x (m) over t(seconds)
P = F_x . x / t
also Power = Force F_x at a set velocity v ( N / s)
P = F_x . v
Rotation
The power transmitted by a rotating shaft = the torque T x the angular velocity.
P = T * ω =
T * 2 * π * n
P (kW) = T(Nm).n (rev/min) / 9 549
Energy
The energy gained by a body during a displacement is equal to the work done by external forces acting upon the body. This includes frictional and non friction forces.
The potential energy is the energy possessed by a body by virtue of its position relative to some datum level.
The change in potential energy (Joules) gained by a mass of M (kg) lifted through a height of h (metres)
ep = M . g n. h
The kinetic energy of a a body by virtue of its motion at uniform linear velocity
ek = 1/2 . m . v 2
The kinetic energy of a a rotating body
ek = 1/2 . I . p 2
Conservation of Energy..
In the absence of any dissipative forces i.e.friction ,
the sum of the potential energy and kinetic energy remains constant.