Heat and Thermodynamics

1.2 Definition of Mechanical Work

Let a force acting on a particle displace it over a distance dr in a direction, making an angle θ with the direction of the force (Fig. 1.1).

 

 

Fig. 1.1 Schematic representation of mechanical work in translational motion

 

Then the mechanical work done by the force is

 

dw = F dr cosθ     (1.16)

 

The work done is a scalar quantity. If X, Y and Z are the Cartesian components of force and if dx, dy and dz are the Cartesian components of displacement dr, then

 

dW = Xdx + Ydy + Zdz     (1.17)

 

Equation 1.17 means that the work done by a force is equal to the work done by its components in their respective ...