The resistance that a raft experiences when it travels in water varies directly as the cube of its speed .
(A) If the speed of the raft doubles, find the ratio of the new resistance to the original resistance .
(B) If the water reistance increase by 72.8%,what is the percentage increase in the speed of the raft?
reference ans: 8:1
20%
Maths Variations (2) - 10 POINT
2007-03-04 4:30 am
回答 (1)
2007-03-04 4:55 am
✔ 最佳答案
R α v³(A)
v' : v = 2 : 1
R' : R = 2³ : 1³ = 8 : 1
(B)
(R' - R)/ R = 72.8%
R' / R = 1.728 = 1.2³
v' / v = 1.2
% increase in speed = (v' - v) / v = 20%
收錄日期: 2021-04-12 23:49:15
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070303000051KK04554