Question

A stone of mass 20 g is projected from a rubber catapult of length 0.1 m and an area of cross-section 10^-6 m² stretched by an amount of 0.04 m. The velocity of the projected stone is ______ m/s.

(Young's modulus of rubber = 0.5 × 10⁹ N/m²)

Options

• 19

• 20

• 21

• 22

Answer 1

A stone of mass 20 g is projected from a rubber catapult of length 0.1 m and an area of cross-section 10^-6 m² stretched by an amount of 0.04 m. The velocity of the projected stone is 20 m/s.

Explanation:

Energy stored in stretched catapult is converted into the kinetic energy of the stone.

`1/2.("YA")/"L"."x"^2 = 1/2"mv"^2`

`(0.5 xx 10^9 xx 10^-6 xx (0.04)^2)/0.1 = 20/1000"v"^2 ⇒ "v"^2 = 400`

∴ v = 20 m/s