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We have talked about three methods of lifting a rock of 100 kg by 1 m.
If we just want to lift the rock, well our force has to balance the weight,
which means you're going to need a 1000 N force,
and we're going to have to exert that force of a 1m, exactly the height of the table.
If we use the pulley, we had a few options. One was a simple pulley with one connection point.
We'd have to exert a force of 1000 N over the full distance of 1 m.
It was a double pulley, we have to exert half that force, but over twice the distance and so on.
If we use an incline plane, well if the angle is 30°,
we have to exert a force of 500 N over a distance of 2 m.
There's a deep and fundamental pattern emerging here.
10001, 5002, 2504, 3333 and so on and now it's time for the breakthrough.
For all of these seemingly entirely different ways of moving this block up by a height of 1 m
something is constant, the force times the distance is always equal to 1000.
10001, 3333, 5002, it doesn't matter. These are all giving you a value of 1000.
This quantity force times distance is so important that we're going
to give it its own name--we're going to call it work.