Help for my Physics Fair Exposition Tommorrow?

Question

Hi guys. Tomorrow in my school i have to make an exposition about my Physics project, a Balsa wood cable-stayed bridge. There is a question I couldn't solve, here it is:

What are the real applications of systems of equations?

I really need to solve this question. If you have an answer you'll be helping me a lot.

THX!

Answer 1

the power of solving systems of equations is that when something is affected by more than one factor, and you can get equations to describe each of those factors, you can set them up in a system so that the solutions are dependent on each of the variables, but you change just one variable and see the effect on other parts of a system.
in the cable stayed bridge example, consider the stress (load per area) on the cables.
the cables have to support the load of the bridge. the cables make an angle with the bridge surface depending on the height of the pier. if the pier is low the cables make a sharp angle with the road surface. this means the surface has to be reinforced to support the lateral stress. but if the pier is tall, the cables become long and heavy and subject to wind influence.
so you can set up a system of equations where the roadway weight can be ralated to the height of the pier. the cable stress can be related to the weight of the road and to the height of the pier and the wind resistance. then the pier load can be related to the weight of roadway, height of pier, length and dia of cables.
Once the system is set up you can change the dia of the cable and see how it changes the weight, the load on the pier and the effect of wind. change the height of pier a bit and you can see the change in piel load, angle of cables to road, stress on roadway. etc.
of course this is way simplified, but it give the idea for your particular project.