Q.If the volumes of two vertical solid cylinders are equal, and their heights are in the ratio 1:2, then the ratio of the lengths of their radii will be – (a) 1: √2 (b) √2:1 (c) 1:2 (d) 2:1
Answer: B
Let the heights be \(h\) units and \(2h\) units, respectively, and the radii be \(r_1\) and \(r_2\).
According to the condition, \(πr_1^2 h = πr_2^2 \times 2h\).
Or, \(\cfrac{r_1^2}{r_2^2} = \cfrac{2h}{h}\).
Or, \(\cfrac{r_1}{r_2} = \sqrt{\cfrac{2}{1}} = \cfrac{\sqrt{2}}{1}\).
∴ \(r_1 : r_2 = \sqrt{2} : 1\).
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