In the fig above W1 = 200g, and W2 =450g . Calculate the extension of the spring per unit load?

[g = 10ms^-2]

• A.6.0 x 10^-5mN^-1
• B.2.5 x 10^-4mN^-1
• C.6.0 x 10 ^-3mN^-1
• D.2.5 x 10 ^-2mN^-1
• E.