A wall, acted upon by a force of 20 N, does not move. The work done on the wall in this process is

0 (Zero)

Explanation:

Definition of work done states that,

Work done on an object is the force applied on that object in the direction of Displacement of the object.

means that,

W = F. dS (Dot product of Force and displacement)

When the wall is acted upon by the force of 20 N, Wall does not move,

Thus, displacement of the wall is zero.

So, W = 20*0 = 0.

Thus, Work done on the wall is zero.