Work, Energy, Power

• Work done by a constant force on an object is defined as the product of the force and its displacement in the direction of the force.
• W = F (s cos $\theta$) (by name)


  W = Work Done

  F = Force

  s = Displacement
• In a force-displacement graph, area under the graph is the amount of work done.
• U = $\frac{1}{2}$ke^2 (in units)


  U = J

  k = N m^-1

  e = m
• Principle of Conservation of Energy states that energy can neither be destroyed nor created in any process. It can be transformed from one form to another, and transferred from one body to another but the total amount remains constant.
• Chemical energy is the energy stored in bonds of chemical compounds and the energy may be released during a chemical reaction.
• Nuclear energy is energy stored in the nucleus of an atom and released through fission, fusion or radioactivity.
• Radiant energy is energy that is trasmitted in the form of electromagnetic radiation.
• Internal energy is energy associated with motion and interaction of atoms and molecules in solids, liquids and gases, in the form of kinetic and potential energy, related to our sensation of temperature.
• Mass energy is energy in the form of mass, given by Einstein's mass-energy equivalence equation. ( $E=$$mc^2$)
• Kinetic energy is energy that all objects possess in motion.
• Electric potential energy is the energy that exists between charges.
• $E_k=$$\frac{1}{2}mv^2$ (in units)


  $E_k$= J

  m = kg

  v = m s^-1
• $E_p=$$mgh$ (in units)


  $E_p$= J

  m = kg

  g = m s^-2

  h = m
• The sum of kinetic energy and potential energy in a body is called mechanical energy.
• Power is defined as work done per unit time. Its SI unit is Watt ( W ).
• Efficiency = Useful Energy Output / Total Energy Input * 100%
• Average Power is the total work done divided by the total time taken.
• Work-Kinetic Energy Theorem states that the net work done by forces acting on a particles on a level surface is equal to the change in kinetic energy of the particle.
• P = Fv (in units)

  P = W

  F = N

  v = m s^-1
• P = W / t (in units)

  P = W

  W = J

  t = s