When I use a lever, I can lift heavier stuff. Where exactly does that additional force come from? Was it inside me all the time, or does it come from somewhere outside of me?
In: Physics
I believe the simplest way to understand it, is with understanding how torque works. The classic example is opening or closing a door that rotates about its hinge. Try opening a door by pushing just next to the hinge and you’ll see you need to push quite hard, compared to when you push the door from where the handle is (this is why the handle is on the far side of the hinge).
So it’s easier to rotate things about an axis when you apply that force further away. In the case of a lever, when you apply a force on one end, the output force is greater because the torque depends on the distances from the axis (or fulcrum).
One way of looking at it is that you’re moving one end of the lever a a lot only to move the other end a little; you apply a force to one end of the lever over a great distance, and that same force is applied over only a short distance on the other.
In a lever, there are three forces. These forces all add up to zero. There is the force applied by your hand, the force applied to your object, and the force applied by the fulcrum. The force applied by your hand and the reaction of the force applied to the object (the object pushing back on the lever) are both in the same direction in a see-saw-type lever. The force from the fulcrum is what keeps the lever from being flung off in this direction.
So, not only does the additional force to lift the object come from the fulcrum, but *all* of the force to lift the object *plus* the force to keep your hand from moving come from the fulcrum.
Work is “force” multiplied by “distance”. One end of the lever moves a large distance but requires little force. The other end of the lever applies a large force but moves little distance. So the total work on either end is the same.
torque- the longer the radius of the lever is, the less force is required to generate the same amount of torque (turning force) . so basically, you can apply the same amount of force to something with a 30 centimeter lever and a 60 centimeter lever, and have a lager amount of torque on the 60 centimeter lever
You use the same force, but for longer distance – you have to pull the lever like 5 times further, to move the heavy stuff for “normal” distance
so your force is multiplied 5 times, but you have to use it for longer.
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