State the conditions under which a force does no work.
1 Answer
A force does not work, when
- the displacement is zero: When the displacement in the direction of the force is zero by the definition of work, w=F×d = F×0 = 0 joules. The examples are, standing the whole day on the ground, pushing the walls of a house.
- the displacement is perpendicular to the direction of the force: When displacement is perpendicular to force applied. This means only one thing. The displacement on the body is not caused by the force we are taking into consideration. Actually, the work done is calculated using the formula, W = F×s×cos(θ), where θ is the angle between force and displacement as shown in the figure
Now if the displacement is perpendicular to the force i.e., θ = 90°, we get
W = F×s×cos(θ) = F×s×cos(90°) = F×s×0 = 0
Things to remember from Work
- Work is said to be done if any object changes its position by the application of force on it.
- The SI unit of work is the joule
- Generally, there are two types of work
- work against gravity,
- work against friction.
- The work done by an object is zero if
- Displacement is zero, and
- Force is perpendicular to the displacement.
Topics from Physics
Physical Quantities
27
Electricity & Magnetism
48
Motion
8
Measurement
4
Electricity
166
Physical Optics
80
Waves
117
Force
51
Heat
137
Laws of Motion
1
Light
100
Pressure
139
Thermodynamics
1
Recommended Note
Related Questions