Question

A boat, with a maximum speed of 8.10 km/hr in still water, is attempting to cross a river. Assume that the water flow is uniform, at a rate 4.11 km/hr and that the boat's direction leads it to land directly across from its starting point. A.)How much time will the trip require if the river is 0.830 km wide, B.) Use a vector diagram to figure out the velocity perpendicular to the shore. Use Distance = speed * time to find the time. The unit for time in the SI system is s (second).

the picture wont post, but it shows a current pointing to the left.

Answer 1

Solution:

a)

The boat will have to head upstream at an angle = sin^-1[4.111/8.10] = 30.5^o

t = D/V_x = 0.83/(8.10*Cos30.5^o) = 0.1189 hr = 7.135 min = 428 s.

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