Data:
[tex] F = 20 [N] [/tex]
[tex] m = 3 [kg] [/tex]
[tex] s = 4 [m] [/tex]
Work is calculated from the following formula:
[tex] W = F \cdot s \cdot cos(a) [/tex]
Where a is the angle between force vector and displacement vector. When force is perpendicular to displacement, a = 90 deg and cosine of this angle = 0.
Therefore, the work this force does = 0 [J]