Respuesta :
Since the crate is moving at a constant speed, then the acceleration of the crate is 0. Then, the net force over the crate is also 0.
You need to exert a force of 5 N to counteract the friction force.
The work done after applying a force F along a distance d is given by the formula:
[tex]W=F\times d[/tex]Remember that this formula is valid only if the force F and the displacement are parallel.
Substitute F=5N and d=5m to find the work:
[tex]W=(5N)(5m)=25N\cdot m=25J[/tex]Therefore, the work that you do in such situation, is:
[tex]25J[/tex]