Question

Calculate the work done to stretch an elastic string by 40cm if a force of 10N produces an extension of 4cm in it?​

Answer 1

The work done to stretch an elastic string by 40cm is 20 Joules

Hooke law states that the force (F) applied to a spring is directly proportional to the extension (e).

F ∝ e

F = ke

k is the constant

Given that a force of 10N produces an extension of 4cm, hence:

F = ke

10 = k(4)

k = 2.5 N/cm

For an extension of 40cm, the work done is:

Work done = (1/2)ke²

Work done = (1/2)(2.5 N/cm)(40 cm)² = 2000Ncm = 20 Nm

Work done = 20 Joules

The work done to stretch an elastic string by 40cm is 20 Joules

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