A drawing pin, a snowshoe and a sharp knife all use the same idea: pressure depends not just on the force, but on the area it is spread over.
Force
Area
Pressure
The pressure equation
Pressure = force ÷ area. The unit is the pascal (Pa), which is one newton per square metre. Squeeze the same force onto a smaller area and the pressure shoots up, which is why a sharp knife or a drawing pin cuts in so easily. Spread it over a large area, like a snowshoe or a tractor tyre, and the pressure drops so you do not sink.
Check yourself
Why does a sharp knife cut better than a blunt one?
A sharp edge has a very small contact area. The same pushing force over that tiny area gives a very high pressure, so it cuts in easily. A blunt edge spreads the force over more area, lowering the pressure.
A force of 100 N acts on an area of 5 m². What is the pressure?
20 Pa. Pressure = force ÷ area = 100 ÷ 5 = 20 pascals (newtons per square metre).
Why do camels and snowshoes have wide feet?
A large contact area spreads the weight out, lowering the pressure on the sand or snow so they do not sink in.