$\dfrac{\delta_1}{2} = \dfrac{\delta_2}{6}$
$\delta_1 = \frac{1}{3}\delta_2$
$\dfrac{64P_1R^3n}{Gd^4} = \dfrac{1}{3} \left( \dfrac{64P_2R^3n}{Gd^4} \right)$
$P_1 = \frac{1}{3}P_2$
$\Sigma M_{at\,\,hinged\,\,support} = 0$
$2P_1 + 6P_2 = 4(98.1)$
$2(\frac{1}{3}P_2) + 6P_2 = 4(98.1)$
$P_2 = 58.86 \, \text{N}$
$P_1 = \frac{1}{3}(58.86) = 19.62 \, \text{N}$
$\tau = \dfrac{16PR}{\pi d^3} \left( 1 + \dfrac{d}{4R} \right)$ → Equation (3-9)
For spring at left:
$\tau_{max1} = \dfrac{16(19.62)(75)}{\pi (10^3)} \left[ 1 + \dfrac{10}{4(75)} \right]$
$\tau_{max1} = 7.744 \, \text{MPa}$ answer
For spring at right:
$\tau_{max2} = \dfrac{16(58.86)(75)}{\pi (10^3)} \left[ 1 + \dfrac{10}{4(75)} \right]$
$\tau_{max2} = 23.232 \, \text{MPa}$ answer
