作者KOREALee (韩国最高)
看板Physics
标题Fw: [问题] 几题微方跟物理有关的应用问题
时间Sun Nov 6 13:11:31 2011
※ [本文转录自 Math 看板 #1EjVdv8N ]
作者: KOREALee (韩国最高) 看板: Math
标题: [微方] 几题微方的应用问题
时间: Sun Nov 6 11:07:33 2011
1.
A tank, having a capacity of 700 gal, initally contains 10 lb of salt
dissolved in 100 gal of water. At time t = 0, a solution containing 0.5 lb
of salt per gallon flows into the tank at a rate of 3 gal/min and the
well-stirred mixture flows out of the tank at a rate of 2 gal/min.
(1). How much time will elapse before the tank is filled to capacity?
(2). What is the salt concentration in the tank when it contains 400 gal
of solution?
(3). What is the salt concentration at the instant the tank is filled to
capacity?
dP P
以下两题 好像会用到 ─── = 0.1 (1 - ───)P 这个公式
dt 3
2.
Suppose the colony starts with 100,000 indivduals. How long will it take the
pop-ulation to reach 90% of its equilibrium value?
3.
Suppose, after 3 years of existence, the colony population is found to be
2,000,000 individuals. What was the initial population?
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※ 转录者: KOREALee (106.1.133.10), 时间: 11/06/2011 13:11:31
1F：推 j0958322080:第一题有点类似火箭 11/06 13:30