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?

2 answers

  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.

  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

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