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Physics on TI-89: String & Tension

April 4, 2014 · by physics · Tension

An elastic string is stretch horizontally between two fixed points 0.08m apart. An object of weight 4.0N is suspended from the midpoints of the string, causing the midpoint to drop 0.12m.

Calculate

a) the angle of each part of the string to the vertical

b) the tension in each part of the string

Raw Transcript

Hello everyone. This is Tom from everystepphysics.com. I’m going to do a problem that’s come up in any number of tests. It states in elastic string is stretched horizontally between two fixed points 0.08m apart. An object of weight 4 Newtons is suspended from the midpoint of the string causing the midpoint to drop a distance of .12 meters. Calculate a, the angle of each party of the string to the vertical and b, the tension in each part in the string. Let’s get started. You put physics in here with closed parentheses open/close parentheses to get my menu. Which I’ve already done. That’s in the instructions of my programs. And we’re going to I’m gonna go to the bottom of the alphabet here scroll up to the T section which is Tension. They ask for Tension and I’m going to go to Tension here. And, we’re going to scroll down to what’s asked for. There’s many many problems for tension but we’re going to scroll down because what what they gave us was weight in Newton’s. Here we have weight and the angle and here we have year we have Newton’s in the distance apart and distance drop. Number B. So we’re going to choose that one. You have to press alpha before before we enter anything in the entry lines here. Alpha and Newton’s weight was 4. The distance apart was .8. Press alpha first, meters. I always give you choices centimeters to meters, they trick you on that. Choose meters; that’s what they gave you. And alpha .12 meters again. I always show you which you’ve entered so you can change it if you want. I say it’s okay. And a lot of times I show you the picture like this. Notice we divided the total distance by 4. There’s one on each side. These are generally in physics, these are trigonometry problems. Geometry problems. So here we have the .12 and here we have the .4, .4. Those equal .8. And we have the theta for the horizontal here. And theta for the vertical here. In case they ask you for something different. And here’s the 4 Newton’s of weight right here. And we press enter and you notice that the vertical is 73.3 which is what they asked for. You write that on your paper. This formula here. In case they ask you for the horizontal. Which generally they do but not in this problem. It’s 16.7 degrees. And the tension is 1/2 4 because 4 is divided by each string. 1/2 of this is 2 of course. And then the cosign of 73.3 is 6.9602. If they ask for the vertical angle you you’d enter this formula. And/or if they ask you for the other one, you could enter this formula. They both come up with the same answer, 6.9602. Pretty neat, huh? everystepphysics.com Go to my site, buy my programs pass your physics classes. And also subscribe to new upcoming videos and blogs.