Physics · 2019
JEE Main · 8 April 2019, Shift 1 · Q7
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…
A boy's catapult is made of rubber cord which is $\displaystyle 42$ cm long, with $\displaystyle 6$ mm diameter of cross-section and of negligible mass. The boy keeps a stone weighing $\displaystyle 0.02$ kg on it and stretches the cord by $\displaystyle 20$ cm by applying a constant force. When released, the stone flies off with a velocity of $\displaystyle 20 \mathrm{~ms}^{-1}$. Neglect the change in the area of cross-section of the cord while stretched. The Young's modulus of rubber is closest to :
Official answer
(1)
$\displaystyle 10^6 \mathrm{Nm}^{-2}$
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JEE Main 2019 Physics question, with the answer from NTA’s final answer key. Where our answers come from.