Want to lie on a nail bed? Physics has a back

Launching the numbers gives me 1,394 nails, which is actually not that much. A 40 x 40 square grid is 1,600 nails, which is more than that to prevent skin piercing.

So what if you replace nails with a bunch of broken glass? It’s really the same thing. Sure, glass can be sharper than nails, but it also has some four parts. As long as the contact area is large enough, the glass won’t hurt anyone.

So that’s the secret: you don’t need hard skin, just a little bit of physics.

Smashing Rocks, Mass and Acceleration

Now, let’s go to the part of the demonstration where a soldier is lying on a nail bed on the chest of a guy who breaks a rock. Here the main lesson in physics involves Newton’s second law. This is the relationship between the net force of an object (F_clean), the mass of the object (m) and the acceleration of the object (a). If the object is forced to move only in one dimension (to make things easier), then we can represent it as the following equation:

The acceleration of an object indicates how the speed of that object changes. So if things stand still, the speed will be constantly zero, which would be zero acceleration. However, even if the object is moving, it can have zero acceleration as long as its speed does not change. If the object is increasing in speed, then it would have a positive value for acceleration. This means that when an object slows down, it has a negative acceleration. (Note: This involves one-dimensional motion.)

Here’s an example: Suppose each of the two people is standing on a skateboard. (They are zero-friction skateboards; you can find them in the physics store.) On one board is an adult with a mass of 80 kilograms, and on the other is a child of 40 kilograms. If I push the adult with a force of 80 newtons, it will give an acceleration of 1 meter per second (1 m / s).²). If I push the child with this force, the acceleration will be twice as high (2 m / s²), as half of the adult mass of the child.