Question

A spring was hung from a hook in the ceiling. A number of different weights were attached to the spring to make it stretch, and the total length of the spring was measured each time is shown in the following table

Weight (kg)	2	4	5	8
Length (cm)	3	4	4.5	6

If the spring has to stretch to 9 cm long, how much weight should be added?

Answer 1

If the spring stretch to 9 cm long,

To find the required weight

Put y = 9, in equation (1)

(1) ⇒ x – 2(9) + 4 = 0

⇒ x – 18 + 4 = 0

⇒ x = 14

Weight to be added is 14 kg.