Question

Suppose a river flows due south with a speed of 2.0 m/s. Given that speed of motorboat relative to water is 4.2 m/s due east.
(a) In what direction should the motorboat head to reach a point on the opposite bank directly east from your starting point?
(b) What is the velocity of the boat relative to the earth?
(c) If you travel a distance of 800 m in the water in total to cross the river, find the time is required to cross the river?

Answer 1

a. Vm - 2i = 4.2.
Vm = 4.2 + 2i = 4.65m/s[25.6o] N. of E. = Velocity and Heading.

b. Vm = 4.65m/s[25.6o].

c. d = Vm*t = 800.
t = 800/Vm = 800/4.65 = 172 s.