Work done by a constant force-The scalar product of the force vector () and the displacement vector (
)
w =
Where is a variable force and
is a small displacement.
The area under the force-displacement curve with the proper algebraic sign represents work done by the force.
Work done by the frictional force :
is zero: When the force applied on a body is insufficient to overcome the friction.
is negative: When the force is large enough to overcome the friction
is positive: When force is applied on a body, which is placed above another body, the work done by the frictional force on the lower body
may be positive.