[填空题]
At serve, a tennis p(.iw9 ot 5vl 5zf-wperlayer aims to hl; l3i7o6na2y61xyih 8 mdos4z(cgmrit the ball horizontally. What minimum speed is required for the ball to cle 6rlixyh y67omn 3 i;c4s8da1go2z(lmar the 0.90-m-high net about 15.0 m from the server if the ball is “launched” from a height of 2.50 m? $\approx$ Where will the ball land if it just clears the net (and will it be “good” in the sense that it lands within 7.0 m of the net)? How long will it be in the air? $\approx$ See Fig. below.
