A swimmer at S in the figure below develops a leg cramp while swimming near the shore of a calm lake and calls for help. A lifeguard at L hears the call. The lifeguard can run 9 m/s and swim 3 m/s. He knows physics and chooses a path that will take the least time to reach the swimmer. Which of the paths shown in the figure does he take?
Path LDS is the best path for him to take. It's the most time efficient given how fast he can swim and how fast he can run.
A swimmer at S in the figure below develops a leg cramp while swimming near the...