A string of length 5cm is extended by 0.04m when a load of 0.8kg is suspended at the end. How far will it extend if a force of 16N is applied? [g = 10ms−2]

A. 0.04m
B. 0.12m
C. 0.01m
D. 0.08m

Correct Answer:

Option D – 0.08m

Explanation

From Hoke’s Law, F = ke, K = Constant of Force

For the first case, Force = mg,

= 0.8 × 10 = 8N

∴ 8 = k × 0.04

k = 8/0.04

= 200Nm−¹

Since K is constant

For the second case, F = ke

F = 200 × e

∴ e = F/200

= 16/200

= 0.08m