The weight (W) that can be supported by a wooden beam varies directly as the square of its diameter (d) and inversely as its length (l).
a What percentage increase in the diameter would be necessary for a beam twice as long to support an equivalent weight?
What percentage change in the weight would be capable of being supported by a beam
three times as long with twice the diameter?
I know how to do this one:
So the weight needs a 33% increase.
But for this question:
What percentage increase in the diameter would be necessary for a beam twice as long to support an equivalent weight?
How do I do this?