1. The problem statement, all variables and given/known data A jack-in-the-box is made using a spring of natural length 0.2m and modulus 100N and a "jack" of mass 0.5kg. When the lid is closed, the spring is compressed to a length of 0.1m. Assuming the spring to be vertical throughout, calculate the maximum distance that the "jack" will rise when the lid is suddenly raised. 2. Relevant equations E.P.E= λx^2/l*1/2 and P.E=mgh where λ=modulus, l=natural length x= extension, m=mass and h= distance. 3. The attempt at a solution I have really attempted to solve the problem using the principle of conversion of energy but really failed to get the exact answer as I expected. Could you guys tell me if there is a much more appropriate way of solving it.