[填空题]
John drops a stone from the top of a cliff which is h metres above sea4acjvjuazayd:r 69a 35m, n( x leve9etztz v/,;+m uj6 ihytp3t )ml. The stone strikes the water surface after 9 seconds. The velocity of the falling stoneu/titpe+ ;jh6)9mvzm,y zt 3 t, $v \mathrm{~m} \mathrm{~s}^{-1}$, t seconds after John releases it, can be modelled by the function
1. Find the velocity of the stone when t=12 , giving your answer to the nearest $ \mathrm{m} \mathrm{s}^{-1}$ . ≈
2. Calculate the value of h , giving your answer to the nearest metre.≈
The velocity of the stone when it reaches the bottom of sea is 10 $\mathrm{~m} \mathrm{~s}^{-1}$ .
3. Determine the depth of sea near the cliff, giving your answer to the nearest metre.≈
