Question

The elongation E of a spring balance varies directly with the applied weight W. If E=2 when W=18, findE when W=13

Answer 1

E varies directly with W:

$E=k*W$

Use the given data to find the value of the constant k:

$\begin{gathered} 2=k*18 \\ k=\frac{2}{18} \\ \\ k=\frac{1}{9} \end{gathered}$

Equation of the relationship:

$E=\frac{1}{9}W$

Use the equation above to find E when W=13:

$\begin{gathered} E=\frac{1}{9}(13) \\ \\ E=\frac{13}{9} \end{gathered}$

Then, E is 13/9, when W=13