My Bridge

For our Honors Freshmen Physics class, we have been assigned to create a balsa wood bridge. This bridge has to be no heavier than 100 grams, with the length around 17 and a half inches, with an inner roadway of at least 3 and a half inches wide. The bridge also cannot have anything wider than 1 inch and it cannot be more than 1/4 of an inch thick. In order to get an A, I have to create a bridge with the requirements above and it must hold at least 120 pounds. For my bridge, I have chosen to build a bridge like the one shown in the diagram above. It is a simple, truss bridge shape that I have looked over and researched to make the best result possible. I have chosen this design for my bridge because it is simple, yet powerful. At this point in time, my bridge is still under construction, but right now it seems to look pretty strong. All in all, I have chosen this simple, yet effective design for my bridge.

Static Equilibrium

Static equilibrium is defined as when all of the particles in a system are at rest and the total force on each particle is permanently zero. Static equilibrium is connected to Newton's First Law of Motion, or the law of inertia. An object that is in static equilibrium has no force acting upon it, therefore remaining in rest.


In fact, we have an example of static equilibrium in our classroom. As shown in the picture above, these little birds are in static equilibrium by being able to balance of their beaks on the shoulders of a wild Charlotte. These three little birds in our classroom are primary examples of static equilibrium. They show this because they have weights in their beaks, enabling them to balance on their beaks. Being in static equilibrium, they can balance on their beaks without falling no matter what surface they are on. In addition, static equilibrium can also apply to bridges. Bridges can be in static equilibrium if the weight on top of the bridge is equal to the amount resistance on the bottom of the bridge. The most effective bridges are in static equilibrium

Bridges

Bridges come in many different shapes and sizes. There are many different kinds of bridges as well. The most popular and common bridges are beam bridges, truss bridges, arch bridges, suspension bridges, and many more.


The first and most simple kind of bridge is the beam bridge. It consists of three main parts which are the pile, the pile base, and the deck, as shown in the diagram above. This type of bridge was the first bridge to be built. In fact, the first beam bridges to be made were made by nature. Then, humans saw the nature bridge and imitated it, then made them more and more advanced as they are today. Beam bridges can either be made by one long piece that spreads across, or it can be made by multiple I-beams, trusses, or box girders. All in all, beam bridges are the most simple of all of the bridges and can easily be made.


The next type of bridge is called a truss bridge. These bridges consist of multiple triangles put together to create a strong base. Truss bridges are usually made with straight, steel bars that are used to make the sides of the triangles. This type of bridge is the oldest type of modern bridges that we see today. This bridge is more complex than beam bridges. Truss bridges consist of floor beams, a deck, stringers, struts, and more as shown in the diagram above. These bridges are the most effective material wise and are still used a lot today.

The next type of bridge are arch bridges. The arch bridges were very popular in ancient times around 1300 BC. They were favored for their natural strength by many. Romans were clever and made arches in door frames as well as bridges because of their strength. A lot of ancient architecture included arches as well. Most arch bridges today are made from steel or concrete and span up to 800 feet. These bridges have many supporting posts and because of their curved shape, they are very strong.

The last type of bridge is a suspension bridge. These bridges have a fairly simple design, but are very powerful and can span for 2,000-7,000 feet long, which is a lot longer than any other type of bridge. In fact, the longest spanning suspension bridge in the world is currently the Akashi Kaikyo Bridge in Japan which spans 6,532 feet. Most suspension bridges today have a truss system beneath the bridge to keep the bridge from bending and twisting.