Work
Work = force x displacement
W = F.S
Conditions for a work
- a force should act on an object
- the object must be displaced.
Positive and negative work
- Negative work – When force and displacement act on opposite directions there is a negative force, work is negative.
W = – F x S = F x (-s)
- Positive work – work done is positive when the force is in the direction of displacement
Energy
- Energy is a capacity to do a work.
- It has the unit of work.
- Unit for energy and work = joule (J)
- 1 kJ = 1000 J
Different forms of energy
- Mechanical energy (Potential energy + kinetic energy)
- Heat energy
- Chemical energy
- Electerical energy
- Light energy
Potential energy
- Potential energy is the energy of a body by virtue of its position or height.
- PE = mgh
- where, m = mass, g = acceleration due to gravity, h = height of the body
- When h = 0, i.e., when the body is on the ground, the poential energy becomes zero.
