Eli5: why are the tips of scissors worse at cutting than the base?
In: 38
The left/right handedness also applies to what people are talking about.
Specifically scissors are designed so that the piece your thumb goes through is the inner blade, and your fingers the outer one. This way the natural way your hand pulls (thumb in, fingers slightly out) will force the blades together, helping cut.
But, if you are left handed and use right-handed scissors, now if you run into a tough material/cut, the natural pressure of your thumb pulling inwards is bad, as it opens the gap between the blades.
The left/right handedness also applies to what people are talking about.
Specifically scissors are designed so that the piece your thumb goes through is the inner blade, and your fingers the outer one. This way the natural way your hand pulls (thumb in, fingers slightly out) will force the blades together, helping cut.
But, if you are left handed and use right-handed scissors, now if you run into a tough material/cut, the natural pressure of your thumb pulling inwards is bad, as it opens the gap between the blades.
The amount of energy dissipated by the scissors is directly proportional to the length of the line cut through the material. Meaning the power (Joules per second) is proportional to the speed of the intersection point between the blades as the angle between the scissors is changed.
Using the angular separation of the blades as an independent variable, the power is proportional to its cotangent. This is a value that is close to 0 when the blades are at a right angle and hardly cutting anything, and approaches infinity when the blades approach being parallel and the intersection point travels infinitely fast. So when the angle is close to zero and the intersection point is near the tip, you have to squeeze harder to keep the angle changing at a constant rate.
The amount of energy dissipated by the scissors is directly proportional to the length of the line cut through the material. Meaning the power (Joules per second) is proportional to the speed of the intersection point between the blades as the angle between the scissors is changed.
Using the angular separation of the blades as an independent variable, the power is proportional to its cotangent. This is a value that is close to 0 when the blades are at a right angle and hardly cutting anything, and approaches infinity when the blades approach being parallel and the intersection point travels infinitely fast. So when the angle is close to zero and the intersection point is near the tip, you have to squeeze harder to keep the angle changing at a constant rate.
Torque. The tips of the scissors are far from the hinge, which means that they have to travel further than the blades at the base do. Because of that, less force is applied at the tips than at the base.
Ever use a nutcracker or seafood sheller like [this](https://m.media-amazon.com/images/I/51lmPrrcVkL._AC_SL1500_.jpg)? You’re going to have a hard time breaking a walnut open by hand, but if you put one in this near the hinge and you squeeze the ends of the handle together, it’s easy. Your hands are traveling a larger distance and applying less force, and the part where you put the nut in is traveling less distance and applying more force. You wouldn’t be able to crack that same walnut by keeping it down by the tips, you want it as close to the hinge as possible to make it easy.
Torque. The tips of the scissors are far from the hinge, which means that they have to travel further than the blades at the base do. Because of that, less force is applied at the tips than at the base.
Ever use a nutcracker or seafood sheller like [this](https://m.media-amazon.com/images/I/51lmPrrcVkL._AC_SL1500_.jpg)? You’re going to have a hard time breaking a walnut open by hand, but if you put one in this near the hinge and you squeeze the ends of the handle together, it’s easy. Your hands are traveling a larger distance and applying less force, and the part where you put the nut in is traveling less distance and applying more force. You wouldn’t be able to crack that same walnut by keeping it down by the tips, you want it as close to the hinge as possible to make it easy.
Torque. The tips of the scissors are far from the hinge, which means that they have to travel further than the blades at the base do. Because of that, less force is applied at the tips than at the base.
Ever use a nutcracker or seafood sheller like [this](https://m.media-amazon.com/images/I/51lmPrrcVkL._AC_SL1500_.jpg)? You’re going to have a hard time breaking a walnut open by hand, but if you put one in this near the hinge and you squeeze the ends of the handle together, it’s easy. Your hands are traveling a larger distance and applying less force, and the part where you put the nut in is traveling less distance and applying more force. You wouldn’t be able to crack that same walnut by keeping it down by the tips, you want it as close to the hinge as possible to make it easy.
Related question: why can’t I use scissors successfully with my left hand (I’m right-handed)?
Related question: why can’t I use scissors successfully with my left hand (I’m right-handed)?
Related question: why can’t I use scissors successfully with my left hand (I’m right-handed)?
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