In Newton’s First Law, it states that an object at rest will stay at rest unless acted upon by some excess force. In this experiment, we determined that an object at rest has no net forces acting upon it. The vector sum of all three forces involved should equal 0 according to Newton’s First Law since the knot is at rest. In order to calculate Fnet, we graphed the force vectors in a diagram to display F1,F2, F3, and Fnet. Fnet in theory should have been 0; on the diagram, the three forces should have created a complete triangle. On all of them, they either completed the triangle or were within .25N of the tail of the first vector. In Part 1, when the tension forces were equal to each other and F3, the Fnet calculated arithmetically and the Fnet graphed in the diagram are quite similar. The one on the diagram was not 0N because of some slight variation when graphing the individual forces. Ideally, all of the Fnet values should be 0. In Part 2, one of the diagrams only displayed F1, F2, and Fnet; the other diagram displayed F1, F2, F3, and Fnet. Fnet on the first one and F3 on the second one are almost exact opposites of each other in direction and exactly the same in magnitude. This shows that the vector sum of F1 and F2 are opposite F3 which would make the sum of all three of them equal to 0.
Sources of Uncertainty
1) Precision of tools- the three main tools used to perform the lab and the follow-up work were: the protractor, the ruler, and the scales. Each of these was only precise to a certain extent. The rule was only precise to one-tenth of a cm, the protractor was only precise to each degree, and the scales were only precise to each quarter of a Newton. Each of these would affect how each force is graphed in the diagrams, thus affecting how we interpret Fnet. Visually, Fnet may be an actual value, but realistically it is 0. The imprecision of these tools affects how accurately we can display the forces.
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