Energy

Energy is the capacity to do work

Energy is the capacity or capability to do work and energy is used when work are done.

The unit for energy is joule J, where

1 J = 1 Nm

which is the same unit as for work.

There can be several forms of energy, including

Energy efficiency is the ratio between useful energy output and input energy, and can be expressed as

μ = E_o/ E_i(1)

where

μ = energy efficiency

E_o= useful energy output

E_i= energy input

It is common to state efficiency as a percentage by multiplying (1) with 100.

A lift moves a mass 10 m up with a force of 100 N. The input energy to the lift is 1500 J. The energy efficiency of the lift can be calculated as

μ = 100 (N) 10 (m) / 1500 (J)

= 0.67 or

= 67 %

1st Law of Thermodynamics The First Law of Thermodynamics simply states that energy can be neither created nor destroyed (conservation of energy). Thus power generation processes and energy sources actually involve conversion of energy from one form to another, rather than creation of energy from nothing
Bernoulli Equation A statement of the conservation of energy in a form useful for solving problems involving fluids. For a non-viscous, incompressible fluid in steady flow, the sum of pressure, potential and kinetic energies per unit volume is constant at any point
Heat, Work and Energy A brief tutorial to heat, work and energy. Including essentials as specific heat and specific heat capacity
Energy and Hydraulic Grade Line The hydraulic grade and the energy line are graphical forms of the Bernoulli equation
Equation of Mechanical Energy The equation of mechanical energy in terms of Energy per Unit Mass, Energy per Unit Volume and Energy per Unit Weight involving head
Flywheel Kinetic Energy Kinetic energy and moment of inertia of a flywheel
Energy Transfer Equation Fluid energy transfer
Potential Energy Elevation and potential energy
Work The amount of work done is the product of the applied force and the distance
Power Power is a measure of the rate at which work is done or energy converted