Awall, 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.

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.

not too sure thinking all accelerations are pointed down