The rubber cord of a catapult has a cross-sectional area of 1 mm² and a total unstretched length of 10 cm. It is stretched to 12 cm and then released to project a stone of mass 5 g. Taking Young's modulus Y of rubber as 5 × 10⁸ N/m², the velocity of projection will be:
Correct answer: B. 20 m/s
- A. 20 cm/s
- B. 20 m/s
- C. 2 m/s
- D. None of these
Explanation
The potential energy stored in the stretched cord is E = (1/2)× Stress × Strain × Volume. This stored energy is convertedinto the stone's kinetic energy (1/2)mv². Solving this energybalance equation for velocity gives 20 m/s.
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