The general formula is u = g*t, where u is the velocity of the body freely falling (in meters per second), t is the time in seconds, g is the gravity acceleration g = 9.81 m/s^2. For example, for t = 2 seconds (one of the examples from list) u = 9.81*2 = 19.62 m/s. For other cases, use the formula and make calculations ON YOUR OWN by the same way, as instructed.