A stone is thrown downward from the top of a 45 m tower at 10 m s⁻¹. Taking g = 10 m s⁻², its speed just before hitting the ground is:
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A stone is thrown downward from the top of a 45 m tower at 10 m s⁻¹. Taking g = 10 m s⁻², its speed just before hitting the ground is:

G1 Physics · Accepted Answer

Using v² = u² + 2gh with downward positive: v² = 10² + 2(10)(45) = 1000. Thus v = 10√10 ≈ 31.6 m s⁻¹, closest to 30 m s⁻¹.