Work is said to be done if a force acting on a body displaces it through some distance in the direction of applied force. Energy and power of a body is associated with the amount of work done by the body.
Let us consider a force
Work done
Case I: When direction of motion and the direction of force is same
Case II: When force and direction of motion are in opposite direction
Case III: When force and direction of motion are perpendicular with each other
Graphically, work can be obtained from the area between the force and displacement axis as shown in figure.
Work is an algebraic quantity having no definite direction. It is a scalar quantity.
In SI system, the unit of force is Newton and the unit of distance covered by the body is metre. Hence, the unit of work done is Newton metre
Work Done Due To Variable Forces
Let us consider a body is covering distance by the application of the variable force. Suppose the variable force displaces the body from
This displacement
Total work done in moving the body from
Thus, the area between the force and the displacement axis gives the work done by variable force.
Q. An object is pulled along the ground by a 75 N force directed 30° above the horizon. How much work is done by the force in pulling the object through 8√3 m?
More on Work, Energy And Power