Why is a short stick harder to break than a long stick?
In: Physics
Leverage. With a longer stick the force you put on the end of the stick causes a ton more force in the middle of the stick. As the stick gets shorter it takes the same force to break the stick but you have less leverage.
It’s because of how stress works in a bending object. To break something, you need to exceed the breaking stress of the material. In a long beam (stick) the stress is much higher for a given torque on the end than a shorter beam. As a result, you need to apply way more torque to a short stick than a long one to exceed the breaking stress, assuming both sticks are the same material.
Mechanical engineer checking in. Next time you have a chance, walk up to a door. Try placing your hand next to the door handle and push it open. Then try placing your hand next to the hinges that attach the door to the wall and push it open again. You’ll notice that it’s a lot easier to open the door if you push near the handle.
What you’re experiencing is the “moment” you are creating on the door. A “moment” is a physics term that is basically a force being applied around a pivot point like the way a door swings around the hinges. The distance the force you are applying from the pivot point is important. The farther away from the pivot point that the force is applied, the less force needed. Force x distance = moment. You can apply the same logic for breaking the stick except now imagine instead of the door being attached to the wall with hinges it is firmly attached and cannot rotate. If you try to break the door where it is attached to the wall it will be easier if you push from farther away.
So assuming all other dimensions are the same, a longer stick will be easier to break because you are applying the force farther from the location it breaks just like when you push on the door.
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