The work done by a constant force in a rectilinear motion is given by:
where F is the magnitude of the force, d is the distance the object moves and θ is the angle between the force vector and the displacement vector. In this case we have that:
0. The magnitude of the force is 20 N
,
1. The distance is 8 m
,
2. The angle between the force and the displacement vector is -25°.
Plugging these values in the expression for the work we have:
Therefore, the work done on the box is 145 J