Why does the needle easily penetrate other objects?
Using the tip of the needle to penetrate the paper, the needle penetrated a small hole in the paper very easily. If you turn around the needle and get a slightly rounded blunt end into the paper, it’s not easy to penetrate the paper. This is because the pressure applied on the paper has different magnitudes. Pressure is the magnitude of pressure applied on a unit area.
When we turn the needle tip and blunt end to the paper, the pressure is equal, but the pressure is different. When pierced by the tip, the force is concentrated evenly on the tip of the needle; while using a blunt end, the force is dispersed on a larger area than the tip. Accordingly, the pressure of the fine needle placed on the paper will be greater than the pressure of the blunt needle. Therefore, the pointed tip of the needle is easier to penetrate the paper than the blunt needle tip.
In life, there are many examples of pressure increases, such as sewing needles, using syringes to inject medicine, nailing walls, using iron knives to cut objects, etc. are concentrated forces on a relatively small area, in order to achieve the purpose of increasing pressure.
But too much pressure often causes trouble.
When you walk on snow-covered ground, your feet often sink. This is because the body’s pressure on the snow-covered soil is too great. If you wear ski shoes, not only do not subside, but you can also ski on the snow as if flying. It turns out that the snowboard is both large and large, increasing the area 20 times more than your feet, which disperses the pressure of your body on the snow-covered ground.
Understanding this, you will immediately realize why the wheels of the tank and the tractor must have long and wide sprockets or why to put a railway track on the sleepers.