Question

A boat moves at 10.8 m/s relative to the water. If the boat is in a river where the current is 2.00 m/s, how long does it take the boat to make a complete round trip of 1 100 m upstream followed by a 1 100-m trip downstream?
336 s
250 s
172 s
297 s
211 s

Answer 1

Answer:

Option E is the correct answer.

Explanation:

Velocity of boat = 10.8 m/s

Velocity of river = 2 m/s

Relative velocity upstream = 10.8 - 2 = 8.8 m/s

            Displacement = Velocity x Time

            1100 = 8.8 x t₁

        Time in upstream, t₁ = 125 s  

Relative velocity downstream = 10.8 + 2 = 12.8 m/s

            Displacement = Velocity x Time

            1100 = 12.8 x t₂

        Time in downstream, t₂ = 86 s  

Total time = t₁ + t₂ = 125 + 86 = 211 s

Option E is the correct answer.