Linear equation in two unknowns using elimination
The distance between place A and place B is 10 km.A sparrow needs 1 hour
to fly from one place to another and then get back.If the time required for the sparrow to fly along the wind is 100m is the same as that required for it to fly 50m against the wind.Find the flying speed of the sparrow in still air (a)km/h and the average wind speed between A and B (b)km/h.
F.3 Math 1 Question only
2008-11-16 2:32 am
回答 (1)
2008-11-16 5:43 am
✔ 最佳答案
a) The sparrow needs 1 hour to fly from A to B and back to A , so it must fly 20 km and the flying speed of the sparrow in still air is 20km/hb) Let y be speed of along wind and z be speed of against wind.
y-z=20---(1)
0.1/y = 0.05/z---(2)
From (2),
y=2z---(3)
Sub.(3)into(1),
2z-z=20
z=20
putting z=20 into (3)
y=2x20
y=40
Therefore the speed of along wind is 20km/h, the speed of against wind is 40km/h,
so the average wind speed is 30km/h [(20+40)/2]
收錄日期: 2021-04-13 16:14:42
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