How to lose a stone in 21 days

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A 2.o-kilogram stone that is dropped from the roof of a building takes 4.0 seconds to reach the ground. Neglecting air resistance, the maximum speed of the stone will be approximately (A) 8.0  m / s (B) 9.8  m / s (C) 29  m / s (D) 39  m / s Base your answers to questions 19 and 20 on the diagram below, which shows a 1-kilogram aluminum sphere and a 3 -kilogram brass sphere, both having the same diameter and both at the same height above the ground. Both spheres are allowed to fall freely. [Negl