#Forces problem key

35 messages · Page 1 of 1 (latest)

zealous harness
inner swanBOT
zealous harness
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can anyone help me understand why in the matrix she is no longer multiplying x and y times f1 and f2

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like its there when she writes down f1 f2 and f3 but then in the matrix its gone

hoary ruin
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F1, F2 and F3 are vectors which were written in coloumns

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x and y refer to the components of that vector

zealous harness
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so shouldnt the matrix output x and y

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also i thought it was f1 times cos(tan...) plus f2times cos(tan...) 0 not without teh Fs

hoary ruin
zealous harness
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could you write it llike a system

hoary ruin
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imagine like

4f1 + 4f2 + f3
5f1 + 4f2 + 2f3

then we can write the system into a **coefficient **matrix

f1 f2 f3
(4 4 1) x
(5 4 2) y

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You know like Ax = b

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the vector x would be your (x,y) basically

hoary ruin
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lemme use other variables

zealous harness
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cuz theres only 2 spots for answers

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it gives x = and y= right

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how does she get the answer from that

hoary ruin
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x = cos(theta)
y = sin(theta)

hoary ruin
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,w {{-cos(arctan(24/7)),cos(arctan(24/10))},{sin(arctan(24/7)),sin(arctan(24/10))}}{{x},{y}}={{0},{15}}

hoary ruin
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,w {{N[-cos(arctan(24/7))],N[cos(arctan(24/10))]},{N[sin(arctan(24/7))],N[sin(arctan(24/10))]}}{{x},{y}}={{0},{15}}

hoary ruin
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here you see the approximated values

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It would have been better if your teacher did a straight line

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the output are the forces f1 and f2

hoary ruin
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,w {{N[-cos(arctan(24/7))],N[cos(arctan(24/10))]},{N[sin(arctan(24/7))],N[sin(arctan(24/10))]}}{{F1},{F2}}={{0},{15}}