An inverted frustum with a depth of 7 cm. The radii of the top and bottom are 4 cm and 3 cm respectively.
a) Find,in terms of Π, the volume of the frustum.
b) If the frustum is filling with water at a speed of 15 cm3 per second, how much time is required to fill the frustum?
個ans係 a) (259Π/3) cm3
b) 19 s
- Brian LuiLv 51 十年前最愛解答
The height of the removed portion of the cone = h cm
h : (h+7) = 3 : 4
h = 21
The height of the complete cone = 21 + 7 = 28 cm
Volume of frustum
= ⅓π(4)²(28) - ⅓π(3)²(21)
= 259π/3 cm3
= (259π/3) / 15
≈ 18.1 seconds
2007-03-11 22:35:22 補充：
For (b), if it is to be rounded up to the next complete second, then it is 19 seconds.
2007-03-11 22:35:32 補充：
For (b), if it is to be rounded-up to the next complete second, then it is 19 seconds.