Question

The amount of extension in an elastic spring varies directly with the weight hung on it. If a weight of 250 gm produces an extension of 3.5 cm, find the extension produced by the weight of 700 gm.

Answer 1

Let x cm be the extension produced by the weight of 700 gm.
 

Weight (in gm)	250	700
Length (in cm)	3.5	x

\[\text{ Since the amount of extension in an elastic spring varies and the weight hung on it is in direct variation, we have } : \]
\[\frac{250}{700} = \frac{3 . 5}{x}\]
\[ \Rightarrow x \times 250 = 3 . 5 \times 700\]
\[ \Rightarrow x = \frac{3 . 5 \times 700}{250}\]
\[ = \frac{2450}{250}\]
\[ = 9 . 8\]
\[\text{ Thus, the required extension will be 9 . 8 cm }  .\]