Work done (Units Nm/J) = Force X distance moved in the direction of the force
Work done = Energy transferred (Energy is
the capacity to do work)
W=Fx
When force is applied at an angle, the following
formula can be used
Conservation of energy
Energy is the capacity for doing work
"Potential" energy can be stored, and converted into other
forms. This includes G.P.E, elastic and electric. Non
potential energy can only be transferred
Principle of conservation of energy - The total energy of a closed system remains constant,
energy can never be created or destroyed, only transferred from one form to another
K.E and G.P.E
K.E is directly proportional to the mass of the object,
and directly proportional to the speed squared
Gravitational Potential energy - The capacity for doing work
as a result of an objects position in a gravitational field
This formula can only be used for a
UNIFORM gravitational field (i.e close
to Earth's surface) where g can be
assumed to remain constant
It is gained with height
Using the idea of W=Fd, the force is Weight
(mg), and the distance is the vertical height
travelled (h), meaning you get G.P.E = mgh
G.P.E can be converted to K.E, e.g with a waterfall or
rollercoaster. By putting them equal to each other, the
final velocity v does not depend on the mass of the
object. It's only true if there are no resistive forces
Power and efficiency
Power is the rate of work done (Or rate of
energy transfer). Units are Js^-1, or Watts
Sometimes, a constant force has to be exerted
to maintain speed, e.g a car on a road.
For the car, the net force is zero, since the
power of the engine is equal to the rate of
work done against frictional forces
This equation can be used for a
variety of situations, like above
All energy in a closed system is conserved, but it does not mean
all energy is converted into useful output energy