5, Work, Energy, Power Flashcards
Def conservation of energy
The total energy of a closed system remains constant. Energy cannot be created or destroyed, only transferred from one form to another.
Define energy
The capacity that something has to do work (since one Joule is equal to one Nm)
Def elastic potential energy
The energy stored in an object as a result of reversible changes in its shape
Def electrical potential energy
Energy of electric charges due to their position in an electrical field
Def internal (heat or thermal) energy
The sum of all the random potential and kinetic energies of the atoms in a system
What is important to remember about KE and GPE which is useful in an exam?
Loss of GPE = gain in KE, therefore:
mgh = 1/2mv^2 (Cancel the mass)
What is the equation for power?
P = W / t
What other ways could you find the work done in the power equation?
Find the change in kinetic energy,
Find the change in GPE
Find the regular work done (force x distance)
What is the second equation for power? (In terms of speed)
Power = force x speed
What is the equation for efficiency percentage?
Efficiency = (useful output energy / total input energy) x 100
What is the main equation for work done?
W = force x distance
