Relative Motion
Swimmer speed relative water 2 m/s; river speed 1 m/s. Width 100 m. Minimum crossing time is:
Select the correct option:
Solution
50 s
To cross the river in minimum time, the swimmer must swim directly perpendicular to the river current (parallel to the width). The time taken to cross is determined only by the component of velocity perpendicular to the river banks (vy). tmin=vswimmerWidth=2 m/s100 m=50 s. Note: While the swimmer will be carried downstream (drift) by the river current, this does not affect the time required to cover the 100 m width.
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About This Question
- Subject
- physics
- Chapter
- kinematics
- Topic
- relative motion
- Difficulty
- Medium
- Year
- 2025
Solution
Correct Answer:
50 s
To cross the river in minimum time, the swimmer must swim directly perpendicular to the river current (parallel to the width). The time taken to cross is determined only by the component of velocity perpendicular to the river banks (vy). tmin=vswimmerWidth=2 m/s100 m=50 s. Note: While the swimmer will be carried downstream (drift) by the river current, this does not affect the time required to cover the 100 m width.
This medium difficulty physics question is from the chapter kinematics, covering the topic of relative motion. It appeared in the 2025 exam.
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