Final answer:
Without the speed of the river current, we cannot determine how far downstream the swimmer will land (part a), but we can calculate the time to reach the opposite bank (part b) as approximately 2 minutes and 8.57 seconds by crossing a 180 m wide river at a speed of 1.4 m/s in still water.
Step-by-step explanation:
The question deals with the concept of relative velocities in Physics, particularly regarding motion in two dimensions. To address part a) of the student's question, we must understand that when the swimmer swims across the river, their velocity relative to the water will not be affected by the river's current in terms of reaching the far bank. However, the current will carry the swimmer downstream. Since we are not given the speed of the current, we cannot calculate how far downstream he will land. The speed of the swimmer only allows us to calculate the time taken to reach the opposite side, which is part b) of the question.
To find out how long it will take the swimmer to reach the other side, we divide the width of the river by the swimmer's speed in still water:
Time = Distance / Speed = 180 m / 1.4 m/s = 128.57 seconds or approximately 2 minutes and 8.57 seconds.