Accepted Answer
You would need the weight of the paper and how high off the ground Alex is going to be lifting them.
Accepted Answer
All you need in order to calculate the work done is the force exerted vertically ("lifting") and the vertical distance through which the force is exerted ("height").Then Work = (force) times (distance).Sadly, if you try to apply this simple definition of 'work' to the data you've given for the situation, your attempt will fail ignominiously. You will say that Alexhas exerted a force of 10 kilograms to lift the documents 5 meters, and hastherefore done (10 x 5) = 50 somethings of work, which is wrong.It's wrong because 'kilogram' is a unit of mass, not one of force.Nothing 'weighs' 10 kilograms.But my first paragraph is the direct answer to your question. The mass of the stack of documents, and the height to which the stack is lifted, will help you compute the amount of work Alex does.