A boat propelled so as to travel with a speed of 0.5m/s in still water, moves directly (in a straight line) across a river that is 60m wide. The river flows with a speed of 0.30m/s. How long in seconds does it take the boat to cross the river?

Answer 1

tanA = 0.3/0.5 = 0.6
A = 31o

D = 60/cos31 = 70 m.

V = 70/cos31 = 0.583 m/s

D = V*t = 70 m.
0.583*t = 70
t = 120.1 s.

Answer 2

RV =√(0.50)²-(0.30)²
=0.4m/s
Data
T=?s
V=0.4m/s
D=60m

V=d/t
T=d/v
T=60/0.4 =150
T=150seconds