Force multiplied by displacement.
In physics, Work against gravity is simply weight multiplied by displacement.
Work by gravity
In the absence of other forces, gravity results in a constant downward acceleration of every freely moving object. Near Earth's surface the acceleration due to gravity is g = 9.8 m.s-2 and the gravitational force on an object of mass m is Fg = mg. It is convenient to imagine this gravitational force concentrated at the center of mass of the object. If an object is displaced upwards or downwards a vertical distance y2 − y1, the work W done on the object by its weight mg is:
W = Fg (y2-y1) = Fg Δy = - mg Δy
where Fg is weight (pounds in imperial units, and newtons in SI units), and Δy is the change in height y. Notice that the work done by gravity depends only on the vertical movement of the object. The presence of friction does not affect the work done on the object by its weight.
Wikipedia, Work (physics), 2019
Work against gravity is simply weight multiplied by displacement. This was known recently, however this was portrayed in the Quran 1400 years before it was discovered. In the Quran work is related to weight.
[Quran 99:7-8] Whoever does work of an atom's weight of good will see it. And whoever does work of an atom's weight of evil will see it.
"Aamal عمل" means work. In this verse "Yaamal يَعْمَلْ" means do work. Here work (W) is linked to weight (mg).
How could an illiterate man who lived 1400 years ago have known that weight is related to work?