Definitions [5]
Define work.
The work done by a force on a body is equal to the product of the force applied and the distance moved by the body in the direction of force i.e.,
Work done = Force × distance moved in the direction of force
Define 'joule'.
The SI unit of work is joule.
1 joule of work is said to be done when a force of 1 newton displaces a body through 1 metre in its own direction.
Define Translational motion.
When a force acts on a rigid body which is free to move, the body starts moving in a straight line in the direction of the force. This is called translational motion.
Define the term energy.
“Capacity of doing work” is called Energy.
Energy, in physics, is the capacity for doing work. It may exist in potential, kinetic, thermal, electrical, chemical, nuclear, or other various forms. There are, moreover, heat and work-i.e., energy in the process of transfer from one body to another.
Work is said to be done only when the force applied on a body makes the body move (i.e., there is a displacement of the body).
Key Points
- The S.I. unit of work is joule (J).
1 joule = 1 newton × 1 metre, i.e., work done when a force of 1 N moves a body 1 m in its direction. - The C.G.S. unit of work is erg.
1 erg = 1 dyne × 1 cm, i.e., work done when a force of 1 dyne moves a body 1 cm in its direction. - The relation between joule and erg is:
1 joule = 10⁷ erg
