cq_1_161

Phy 201

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.

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What 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 have no idea how to slove this...can you give me some hint.

The only guess i can think of is 5+10=15 and 9+17=26

so tension could be squre roo of15+26=6.4

Dont know how to go any furtehr.

To find the tension you need to find the length.

The length runs from one of the given points to the other. Can you find the distance between the two given points?

What is the vector from the first point to the second?

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To put this question in the context of vectors:

A displacement vector from one point to another is a vector of the

form

<x displacement, y displacement>

The vector represents how you would move (more or less, how far you

would have to go in each direction) to get from one point to another. 

The magnitude of the displacement vector is

magnitude = sqrt( (x displacement)^2 + (y displacement)^2 )

and the angle of the vector with the positive x direction is

angle = arcTan ( (y displacement) / (x displacement) ), plus 180

deg if the x displacement is negative.

For the present question:

What is the horizontal displacement from the first point to the

second? 

What is the vertical displacement from the first point to the

second? 

What therefore is the vector from the first point to the second? 

(You can either give the vector in the form <x displacement, y

displacement> or you can give its magnitude and angle; the two forms are

equivalent.  The first form is the simpler form, and this form will

probably be your choice).

What is the magnitude of this vector?

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What 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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What vector do you get when you multiply this new vector by the tension?

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What are the x and y coordinates of the new vector?

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10 mns

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I am sorry but my brain is not going in any direction for these question.

Do we have to use the x sine theta and y sine theta formula.

See my notes, which should help you get started. Also note the Introductory Problem Set 5 questions assigned previously, I believe in Asst 14.