A ship makes a round trip along a river in time t₀ when water is still, moving at 2 m s⁻¹. On another day a current of 1 m s⁻¹ assists the outward trip and opposes the return. If the round-trip time is t, find t/t₀.
Options

Question

A ship makes a round trip along a river in time t₀ when water is still, moving at 2 m s⁻¹. On another day a current of 1 m s⁻¹ assists the outward trip and opposes the return. If the round-trip time is t, find t/t₀.

Options

G1 Physics · Accepted Answer

Let one-way distance be L. In still water, t₀=2L/2=L. With current: speeds are 3 and 1 m s⁻¹, so t=L/3+L=4L/3. Hence t/t₀=4/3. Option B.