Say I was compressing a spring with high k value in a vice (not sure why I’d want to do that but it’s hypothetical).
As F =k(dx), there would be a force acting back against the vice when I compress the spring. In practice, how can the vice stay put and not unwind when a force is pushing back on it?
In: 3
Same way a wedge can stop a door. The more you push on the door, the more the wedge is compressed. The friction of the wedge (screw threads) with the floor and door (vice) is more than the force that you apply to the door (vice).
You can make a different outcome if you change the angle of the wedge (screw thread). For metal on metal, you need a very coarse screw, with the lenght of a twist similar or above the screw diameter.
Example twisting pliers: https://www.u-buy.jp/productimg/?image=aHR0cHM6Ly9tLm1lZGlhLWFtYXpvbi5jb20vaW1hZ2VzL0kvNzE4Q2RGd013NUwuX0FDX1NMMTUwMF8uanBn.jpg
Or, you can change the friction coefficient, for example, using a screw with recirculating balls, that is basically a frictionless screw. There are more applications for screws with high friction than the ones with no friction, but they exist.
Example recirculating balls:
https://www.larescorp.com/media/1353/recirculating_balls.jpg
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