from the question, u = 40 m/s    g = 10 m/s²     h = ?,     v = 0,     s = ?

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(i) from the formula, v² = u² – 2gh

0 = (40)² – 2 × 10 × h

20h = 1600

h = 1600/20

h = 80m

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(ii) Net displacement = 0 (Because the stone returns back to the surface after reaching the maximum height.

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(iii) Total distance covered by the stone = 80 m + 80 m

                                                                   = 160m