JEE Mains · Physics · STD 11- 8. mechanical properties of solids
A boy’s catapult is made of rubber cord which is \(42\, cm\) long, with \(6\, mm\) diameter of cross -section and of negligible mass. The boy keeps a stone weighing \(0.02\, kg\) on it and stretches the cord by \(20\, cm\) by applying a constant force. When released, the stone flies off with a velocity of \(20\, ms^{-1}\). Neglect the change in the area of cross section of the cord while stretched. The Young’s modulus of rubber is closest to
- A \(10^3\, Nm^{-2}\)
- B \(10^6\, Nm^{-2}\)
- C \(10^8\, Nm^{-2}\)
- D \(10^4\, Nm^{-2}\)
Answer & Solution
Correct Answer
(B) \(10^6\, Nm^{-2}\)
Step-by-step Solution
Detailed explanation
\(Energy\,of\,catapult = \frac{1}{2} \times {\left( {\frac{{\Delta \ell }}{\ell }} \right)^2} \times Y \times A \times \ell \) \( = Kinetic\,energy\,of\,the\,ball = \frac{1}{2}\,m{V^2}\)…
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