1. The problem statement, all variables and given/known data Hello, guys! This problem is from exercise D, Q4 http://www.studyjapan.go.jp/pdf/questions/10/ga-phy.pdf" Consider two springs of negligible mass that have the same natural length (50 cm) and same spring constant. As shown in Figure 1 (view the link), the two srpings are joined together, and then are suspended vertically, with the lower end also fixed in place. Next, as shown in Figure 2, when small object A (mass: 500 g) is attached at the point where the springs are joined, object A descends 20 cm and comes to rest. A is pulled downward and released gently. How much time elapses from release until A reaches its maximum height? 2. Relevant equations F=kx P=mg The upper spring makes a force vertically upward on the mass, and so does the lower spring. Their length variation is the same. So, 2F=P, 2kx=mg 3. The attempt at a solution Since object A comes at rest, the value of the spring constant k can be calculated. 2kx=mg, k=mg/2x -> k=0.5x9.8/2x0.2=12.25 N/m From now on, I don't really know what to do. I've tried to use energy and work, but it didn't help me out, since time didn't come up. I can't even use Simple harmonic motion, cause the force isn't a constant, so acceleration won't be, too... Well, if someone figures a way out, that would be very helpful! Thanks a lot, Tntgsh.