I):final velocity=initial velocity+acceleration due to gravity*time of travel
Therefore,
v=0+9.8*3.1
=30.38 m/s
If by floor you meant water bed then i think there isn't enough info in the question.
Interval training is simply alternating short bursts (about 30 seconds) of intense activity with longer intervals (about 1 to 2 minutes) of less intense activity. For instance, if your exercise is walking and you're in good shape, you might add short bursts of jogging into your regular brisk walks.
