Work in Physics

Work physics is generally said to be the measure of the energy transfer that occurs when an object is moved over a distance, by an external force in the direction of the displacement. Here, we are going to discover more about the topic work, how it's done and what causes work to be done. If force is constant then we can say that the work may be computed by multiplying the length of the path by the component of the force acting along the path. 

Work and Energy

To express this concept of work in a mathematical format, we can write the work as W is equal to the force which is denoted by letter f times the distance d. Or the work or W = fd. If the force is being exerted on any of the objects at an angle θ to the displacement, then we can say that the work done is: 

W = fd cos θ. 

Work which is done on a body is said to be accomplished not only by a displacement which is caused but as a whole from one place to another.  For example, we can say that a gas which is being compressed by rotating a shaft and even by causing invisible motions of the particles which are within a body is by a force which is external which is and magnetic as well.

No work in this context is done unless the object is displaced in some or the other way. And there is a component of the force along the path over which the object is generally moved. The heavy holding which is of the stationary object does not transfer energy to it this is because there is no displacement.  The holding of the end of a rope on which an object or we can say that the heavy object is being swung around at constant speed in a circle does not transfer energy to the object. This is because the force is toward the centre of the circle that too it is at a right angle to the displacement. No work is done in both cases.

The expression of all these scenarios mathematically for work usually depends upon the particular circumstances. 

• The phenomenon of work done in compressing gas at a constant temperature which may be expressed as the product of pressure denoted by letter P times the change in volume that is dV. We can write as  W = PdV. 

• The work which is said to be done by a torque denoted by letter T in rotating a shaft through an angle φ may be expressed as the product of the torque times the angular displacement that is written as W = Tφ.

The work which is done on a body is equal to the increase in the energy of the body. for work energy transfers to the body. So we can say that however, the force which is applied is opposite in direction of the motion of the object then also,  the work is considered to be negative. This generally implies that energy is taken from the object. The units in which work is expressed are the same as those which we usually use for energy that is for example in SI (International System of Units) and the metre-kilogram-second system, and joule (newton-metre) as well; in the centimetre-gram-second system, erg (dyne-centimetre); and in the English system, foot-pound.

Work by Friction

In subjects like physics, work is the energy which is transferred to or from an object via the application of force along the displacement. In its simplest form, we can say that it is often represented as the product of force and displacement. A force which is generally said to do positive work if or when applied on an object has a component in the direction of the displacement of the point of application. A force generally does negative work if it has a component which is opposite in direction of the displacement at the point of the force application.

For example, we can say that when a ball is held above the ground and then dropped, the work which is done by the gravitational force on the ball as it falls down is said to be equal to the weight of the ball. A force which is multiplied by the distance to the ground is a displacement.

Work Energy

The force which is constraint determines the object's displacement in the system. So we can say that limiting it within a range. Taking an example in the case of a slope plus gravity, that is the object is stuck to the slope and then when it is attached to a taut string at that time it cannot move in an outwards direction. That is we can say to make the string any 'tauter'. It generally eliminates all displacements which are in that direction. That is we can say that the velocity in the direction of the constraint is limited to 0 so that the force which is the constraint forces do not perform work on the system.

For a system which is the mechanical system the force which is constraint forces eliminate movement in directions that characterize the constraint. Thus we can conclude that by the virtual work done by the forces of constraint is zero that is a result which is only true if friction forces are excluded.

The Fixed and the frictionless constraint forces do not perform work on the system as the angle which is between the motion and the constraint forces, is always 90°. For example, we see that workless constraints are:  the interconnections which are rigid between particles and then sliding motion on a frictionless surface and rolling contact without slipping.