prepwalk

1. PHYSICS
WORK, ENERGY AND POWER
Short revision series

2. Work
 Work is done when a force moves a body
through a distance in direction of the force,
and is equal to the product of force and the
distance moved
 W = F x s
 W = F x s cos θ (*when considering angle
of the direction)
 SI Unit = Joule
 A JOULE is when a force of 1N moves a body
a distance of 1m.

3. Work done in a field
 W = F x s
 W = mgs

4. Energy
 Capacity to do work
 Also measured in J
 Principle of conservation of energy = in a
closed system the total amount of energy is
constant
Mechanical energy can be K.E or P.E
K.E = ½ mv2
P.E = F x s= mgh

5. Law of conservation of mechanical
energy
 P.E + K.E = constant
 P.E + K.E at point A = P.E + K.E at point B
 ½ mv2 = mgh

6. Power
 Time rate of doing a work measured in watts
W.
 = work done = F x s = F x s/t =Force x velocity
time taken t