Journal Entry 5/1

(Q) Why does a tank have treads?
(A) A flat piece of rubber has a large area that touches the ground. The tank itself has a constant force, regardless of the terrain that it covers. When an object has a force and a large area, its pressure is not very large. The addition of treads to the rubber breaks up the area though. Even with the same force, but with a smaller area in contact with the ground, the pressure of the truck is increased. If the tank has a larger pressure, it is better equipped to go through a rugged landscape.

(Q) How do cleats work?
(A) Cleats are similar to treads on a tank. If you are wearing a basic sneaker, a large area of rubber is touching the ground. Your weight does not fluctuate while wearing the sneakers, so your force is constant. Therefore, with a force and a large area, the pressure will be small. Cleats help to increase an athletes pressure because they reduce the surface area of the shoe. The spikes on the bottom of the cleat have less area than a flat piece of rubber. When the force remains the same, but the area is reduced, the pressure increases. This is good because it helps athletes grip the ground while playing their sport, and it reduces the time they spend on the ground as a result of slipping and falling.

(Q) Why does a pin have a dull end and a sharp end?
(A) The purpose of a pin is to be used by a person to sew. It needs to have two pressures. Low pressure is necessary to enable the use/holding of the pin and high pressure is necessary to puncture the fabric. In terms of a pin, the dull end has a large area. The user's force on the pin does not fluctuate. With a force and a large area, there is a small pressure. The sharp end of the pin has a smaller area than the dull end. Because the force of the user on the pin has not changed, the pressure is increased with a smaller area. This is great because pins can be used to hang things up and they do not make people bleed, unless they push from the wrong end of course!