The work done in extending a spring by 40 mm is 1.52J. Calculate the elastic constant of the spring.
A. 38.8 Nm
-1B. 60.8 Nm
-1C. 190.0 Nm
-1D. 1900.0 Nm
-1 
E. 3800.0 Nm
-1 Correct Answer: D
Explanation
Force = Elastic constant x extension
Work done = \(\frac{1}{2} K \times e^2\)
Given Work done = 1.52J; Elastic constant (k) = ?; e = 40mm = 0.04 m
\(\therefore 1.52 = \frac{k \times (0.04)^2}{2}\)
\(3.04 = k \times 1.6 \times 10^{-3}\)
\(k = \frac{3.04}{1.6} \times 10^3\)
= 1.9 x 10\(^3\)
= 1900 Nm\(^{-1}\)
