Physics lab:9 Equilibrium of parallel force 11/09/2012 By: Camilo Salazar Jillian Ellis Purpose: To understand the conditions need for a rigid body to be in equilibrium when there are forces acting on the body from different sides. Theory: When force is applied on a rigid body for example a ruler it can either be in equilibrium or it can be unbalance. When the force is unbalance what would happen is this motion the body can be either translational or rotational. “A body in translational motion is when all the points within it move in lines that are parallel to each other. (Physics lab pg. 81). Rotational motion is when all points move in a circle motion within or outside the body. A body can have both states at the same time. An unbalance forces will make some sort of motion but when the force are equal to each other they will cancel each other out. This will cause the body to be in a state of equilibrium. There are three conditions to put the body in equilibrium. Condition one “The sum of all forces acting vertically upwards (on a body) must be equal to the sum of all forces acting vertically downward. (Physics lab pg. 81). Condition two: “The sum of all forces acting horizontally to the right must be equal to the sum of all forces acting horizontally to the left. Condition 3: The sum of all of all clockwise torques must be equal to the sum of all the counterclockwise torques. The torques due to a force about a point is defined as the product of the force and the perpendicular distance from the point to the line of action of the force. This can also be written as Tcm=Tccm. Equipment: Ruler Weights A metal poll Hangers Procedure:

The first thing we did to start this lab was to set up the experiment and find the equilibrium point. This can be bit tricky because you have to be sure that everything is equal and it not being tilled. Once this is done you will add weight and measure the point from the origin to see what the distance was to find equilibrium. After you have for you equilibrium point you must you can start adding the weight on the each side. When we add the weight on both sides on one of the side the weight is going to lighter and you must find on which point you can find the equilibrium point.

Once we have finish that we will add several different weights to see if we can find the equilibrium point. Record all data and then after everything is found use the equation to find the calculated answer. Discussion: . This lab was a little tricky because at first we weren’t able to find the equilibrium point for the ruler. After several trails it still wouldn’t work but then we decided that it would be best to switch the ruler and it work fine. Another thing that took us a little while to do was the find the equilibrium point for the weights because we had to slow be sure the it was in equilibrium.

But wither from that once we got the hang of thing the rest of the lab be easy. Conclusion: During this lab we phone that the three conditions does hold and the body needs to place correctly. If it isn’t then the whole body would be starting to rotate which will cause the object to not be in equilibrium. The calculations for the lab will be in the calculations section this lab. Because of our trails for this lab we were able to measure and find the equilibrium on this lab.