A student throws two rocks from the top of a cliff at the same initial speed. The rocks are thrown exactly one second apart, and land simultaneously at the same spot on the ground, 25 meters away from the launch point, as shown in the diagram. Find the flight time of the second rock.

Use g = 10 m/s2.

The March, April, and May issues of Challenges attracted many submissions from all over the world, marking a great finish of the 2021/22 “season.” Alas, the students’ participation has been lacking somewhat. We urge the instructors to share the Challenges with their students and encourage them to submit their own solutions.

We are pleased to recognize the following contributors:

  • Salvatore Basile (Università degli Studi di Palermo, Palermo, Italy)

  • Philip Blanco (Grossmont College, El Cajon, CA)

  • Phil Cahill (The SI Organization, Inc., Rosemont, PA)

  • Norman Derby (Southwestern Oregon Community College,...

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