SOLUTION: A man is rowing at 8 km/h in a river 1.5 km wide in which the current is 5 km/h. (a) In what direction should he head in order to get across the river in the shortest possible time

Question 1144025: A man is rowing at 8 km/h in a river 1.5 km wide in which the current is 5 km/h. (a) In what direction should he head in order to get across the river in the shortest possible time? (b) How much time will he take if he goes in this direction? (c) How far downstream will the boat have gone when it reaches the opposite side?
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
A man is rowing at 8 km/h in a river 1.5 km wide in which the current is 5 km/h.
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(a) In what direction should he head in order to get across the river in the shortest possible time?
Perpendicular to the sides of the river.
Note: this is the shortest time, not the shortest distance.
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(b) How much time will he take if he goes in this direction?
d = r*t
t = d/r = 1.5/8 = 0.1875 hours = 11.25 minutes
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(c) How far downstream will the boat have gone when it reaches the opposite side?
0.1875 hr * 5 km/hr = 0.9375 km

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