Question

A cube of gelatin of $7cm$ side on an edge is resting in a dish with bottom face fixed. Pushing horizontally on the top face with a force of $0.21N$ causes the top to undergo a displacement of $3mm$. Then, the rigidity modulus of gelatin is

• A. $100N/m$${}^2$
• B. $10N/m$${}^2$
• C. $1000N/m$${}^2$
• D. ${10}^4$$N/m$${}^2$

Answer 1

Answer: (C)

$1000N/m$${}^2$

$F=0.21N$
$RM=\frac{\frac{.21}{7\times 7\times {10}^{-4}}}{\frac{.3}{7}}$$=\frac{.21\times {10}^4}{7\times .30}$$={10}^{3}N/m^2$ (using standard result)