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    Hello, I feel a bit embarrased for asking this as I ought to know really, but the physics papers I've been sitting have had a few answers which state that 'so and so is not proportional to so and so because the straight line graph does not pass through the origin'. I thought that as long as the graph was linear, one variable was directly proportional to the other; the offset from the origin was due to a constant, i.e. y=mx+c. Am I wrong?

    Example: (taken from the Jan 2010 OCR AS G452 Paper) 'Is the frequency directly proportional to the temperature?' Answer: (Test: constant f:T /straight line graph through origin) (1)


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    (Original post by Benjamin.F)
    Hello, I feel a bit embarrased for asking this as I ought to know really, but the physics papers I've been sitting have had a few answers which state that 'so and so is not proportional to so and so because the straight line graph does not pass through the origin'. I thought that as long as the graph was linear, one variable was directly proportional to the other; the offset from the origin was due to a constant, i.e. y=mx+c. Am I wrong?

    Example: (taken from the Jan 2010 OCR AS G452 Paper) 'Is the frequency directly proportional to the temperature?' Answer: (Test: constant f:T /straight line graph through origin) (1)


    Thanks for reading this!
    no

    if y is proportional to x, y \ \alpha  \ x it is in the form of y = kx i.e. no constant added

    to be directly proportional, the line has to pass through the origin as well as be linear
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    Oh okay. That's my fail, so much for A-level maths. Thanks!
 
 
 
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