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Phy 121
Your 'cq_1_16.1' report has been received. Scroll down through the document to see any comments I might have inserted, and my final comment at the end.
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A rubber band has no tension until it reaches a length of 7.5 cm. Beyond that length its tension increases by .7 Newtons for every additional centimeter of length.
標hat will be its tension if its endpoints are at the points (5 cm, 9 cm) and (10 cm, 17 cm) as measured on an x-y coordinate system?
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I suppose that after we graph the points, we connect them together and then find the slope.
Now I am not sure how to find the tension from here other than to start from 7.5 and add a .7 until we reach either 10 or 17, but I am not sure, this problem confuses me.
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標hat is the vector from the first point to the second?
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You need to find the length of the rubber band.
To get from (5 cm, 9 cm) to (10 cm, 17 cm) you need to go 5 cm in the x direction and 8 cm in the y direction.
So a vector from the first point to the second has x component 5 cm and y component 8 cm.
You can find the length (and the angle) of this vector, using the techniques of Introductory Problem Set 5.
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I am not sure if it is asking for the direction of the vector, or the slope or what here. I got my slope equal to 8/5.
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You are on the right track. The slope is indeed 8/5. So you already have found the x and y components of the vector.
From this you can easily find the length, which is the magnitude of the vector.
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標hat is the magnitude of this vector?
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I'm sorry I just don't understand what to do in this problem. I looked in the class notes and on the DVD's, but I just can't figure out how to do this.
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標hat vector do you get when you divide this vector by its magnitude? (Specify the x and y components of the resulting vector).
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I'm sorry, I don't know what this is asking for.
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Find the magnitude of the vector, using the usual techniques.
Then divide the x and y components of the vector by the length.
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謬he new vector should have magnitude 1. When you divide a vector by its magnitude the result is a vector with magnitude 1. We call a vector of magnitude 1 a unit vector. What vector do you get when you multiply this new vector (i.e., the unit vector) by the tension?
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You will multiply the components of the new vector by the tension.
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標hat are the x and y components of the new vector?
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This new vector is called the tension vector. It is a force vector which represents the tension. A force vector can be specified by its components, or equivalently by its magnitude and direction.
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You need to use the techniques you learned in Intro Problem Set 5 to answer these questions.
There's a lot to learn here about vectors. I recommend that you spend 20 minutes or so reading my comments and making revisions before checking the discussion below.
&#See any notes I might have inserted into your document, and before looking at the link below see if you can modify your solutions. If there are no notes, this does not mean that your solution is completely correct.
Then please compare your old and new solutions with the expanded discussion at the link
Solution
Self-critique your solutions, if this is necessary, according to the usual criteria. Insert any revisions, questions, etc. into a copy of this posted document. Mark any insertions with &&&& so they can be easily identified.If your solution is completely consistent with the given solution, you need do nothing further with this problem. &#
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