The spring shown above is compressed by Dx from its equilibrium position. When released it launches a block across a frictionless surface with speed of 4 m/sec. The two springs in the following figure are identical to the spring shown above and are also compressed Dx to launch an identical block.

What is the blocks new speed as it passes through equilibrium?

2 m/sec

0.18 m/sec

5.7 m/sec

8 m/sec