In order to accomplish work on an object there must be a force exerted on the object and it must move in the direction of the force. ... For the special case of a constant force, the work may be calculated by multiplying the distance times the component of force which acts in the direction of motion.
Limitations of Van der waal's equation. (i) The value of 'b' is not constant but varies with pressure and temperature. (ii) The value of is not equal to 3b, but actually it is equal to, in some case; and in other cases 2b. (iii) The value of is not equal to but it is usually more than 3 for most of the gases.
