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?
A)250 s
B)172 s
C)211 s
D)297 s
E)336 s

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?
A)250 s
B)172 s
C)211 s
D)297 s
E)​336 s

Quizplus · Accepted Answer

The boat's effective speed upstream is 10.8 m/s - 2.0 m/s = 8.8 m/s, and downstream is 10.8 m/s + 2.0 m/s = 12.8 m/s. Time taken upstream = 1100 m / 8.8 m/s = 125 s, and downstream = 1100 m / 12.8 m/s = 85.94 s. Total time = 125 s + 85.94 s = 210.94 s, which rounds to 211 s.

A Boat Moves at 10