A stone is dropped from a building and 2 s later another stone is dropped from the same point. Both are released from rest. How far apart are the stones when the first stone reaches a speed of 30 m s⁻¹? Take g=10 m s⁻².
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Question

A stone is dropped from a building and 2 s later another stone is dropped from the same point. Both are released from rest. How far apart are the stones when the first stone reaches a speed of 30 m s⁻¹? Take g=10 m s⁻².

Options

G1 Physics · Accepted Answer

First stone reaches 30 m s⁻¹ after 3 s. Then the second stone has been falling for 1 s. Distances: s₁=5(3²)=45 m and s₂=5(1²)=5 m. Separation=40 m. Option D.