Question

If manuel weighs 375 n and is holding the box. how much force is the floor exerting on him? (include direction)

Answer 1

 The box is exerting a force of its weight. So we'll use W=mg (Note: you can use the notation F=ma, doesn't matter since weight IS a force.) We can call g negative since it's directed down towards the earth. 

W = 5kg(-9.8 m/(s^2)) = -49 N 

Thus, the box exerts a force of 49N downwards.