Journal 5/02

- A pin has a dull end and a sharp end because the dull end has a larger surface area so it won't have as much pressure on your finger so you can push harder and the harder you push, the more pressure is on the sharper point that has a lot more pressure with the much smaller surface area.

- A tank has such large treads because of the weight of the tank, it is very difficult for it to be maneuvered around. The large treads have a large area in contact with the ground so therfore less pressure which makes it easier for the tank to move and take turns. The weight of the tank is spread out over so much area that it wont indent the ground as much as if it had 4 normal wheels.

- People sleep on mattresses because the mattress conforms to your body and therefore has way more contact with your body verses the flat floor. All the pressure of your bodyweight is distributed over most of your body when on a mattress, while on the floor all the pressure goes to the areas only in contact and the floor has much less area in contact.