HPQ:Physics:FreeFalling:KS4:Sergio Fabbri

A 10-kg object X is falling freely from a height of 9.0 m. A 20-kg object Y is falling from the same height. If X reaches the ground at a speed of 13.3 m/s, what is the speed that the object Y reaches the ground with?

A. 6.65 m/s

B. 9.81 m/s

C. 13.3 m/s

D. 23.9 km/h

E. 26.6 m/s

Ans. C

CONTEXT Age 14, students are studying free falling objects (dynamics) and they are facing the counterintuitive concept that objects with different "weight" have the same acceleration. This HPQ allows a quick test. I gave some (in a sense, useless) data because sometimes 14-y-old students heavily struggles against abstract reasonings.. However, when they see how easy is the correct answer, they begin to appreciate theory.


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