posted by nicolas .
a rock is tossed straight up with a speed of 30m/s. when it returns it falls into a hole 10m deep. what is the rocks velocity as it hits the bottom of the whole? how long would the rock in the air, form the instant it is released until it hits the bottom on the hole
s = vot + 1/2 at^2 = 30t - 4.9t^2
solve for s = -10. t = 6.439s
v = 30 - 9.8*6.439 = -33.1m/s
Makes sense, since it will be going -30m/s as it starts into the hole.