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What is the difference between directly proportional and proportional?

nettogrof

(on a graph)

Thanks :smile:

Nothing.

Original post by nettogrof

(on a graph)

Thanks :smile:

proportional is a lazy way of saying directly proportional

Reply 3

nettogrof

Thanks for your reply @offhegoes and @TeeEm !! Oh that's strange I thought they were slightly different in some way, so are they exactly the same? I'm asking this because I am trying to write a hypothesis for my physics ISA - it is currently 'The resistance of an LDR will increase as thedistance between the light bulb and the LDR increases' however I would like to expand on it further and either make a quantitative prediction too or predict the relationship between the resistance and distance but I don't now much about graphical relationships :frown:

Reply 4

Jpw1097

Original post by nettogrof

(on a graph)

Thanks :smile:

I always thought that proportional was when if one variable increases then the other increases. For example, if x increases, y must also increase however it may not necessarily pass through the origin.

Directly proportional is when if one variable increases by a certain factor, the other also increases by the same factor. So for example if x doubles, y also doubles. On a graph this is a straight like through the origin.