Answer:
800 Newtons.
Step-by-step explanation:
Work is defined as the force applied to an object multiplied by the distance over which the force is applied. The formula for work is W = F x d.
In this case, the force required to lift the box is equal to the work done divided by the distance.
F = W / d
F = 800 J / 5 m
To convert Joules to newtons, we need to use the relation 1 Joule = 1 Newton x Meter
F = 800 N
So the box weighed 800 Newtons.