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 area of cross-section of the cord while stretched. The Young's modulus of rubber is closest to:

A boy's catapult is made of rubber cord which is 42 cm long, with 6 mm

1.	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 area of cross-section of the cord while stretched. The Young's modulus of rubber is closest to:
A.	106 Nm-2
B.	104 Nm-2
C.	108 Nm-2
D.	103 Nm-2
Answer» B. 104 Nm-2