As can be seen from the picture, a, b, c, d? The horizontal displacement between these four points is equal, that is, x=2L, so these four points are equal time intervals. The difference between two adjacent displacements in the vertical direction is a constant value, that is, △y=gT2=L, and then according to v0=xt.

Solve v0=2Lg and substitute the data into v0 = 0.70m/s.

So, the answer is: 2Lg；; 0.70 m/s