Physics

Physics

Problem

Stone 1 is dropped from rest from a height of 45 m45\,\text{m} above the ground at the same instant that Stone 2 is dropped from rest from a height of 20 m20\,\text{m} above the ground. Taking g=10 m/s2g = 10\,\text{m/s}^2, the time interval between the moments the two stones reach the ground is a) 2 s2\,\text{s} b) 1 s1\,\text{s} c) 0 s0\,\text{s} d) 2.5 s2.5\,\text{s}
Intuitive explanation

The key insight is that each stone falls independently under gravity, so you need to find how long each one takes to hit the ground using the kinematic equation for free fall, then subtract to find the time difference. Since both start from rest, the stone dropped from greater height will take longer—and the time to fall depends on the square root of the distance, not the distance itself.

Intuitive explanation

The key insight is that each stone falls independently under gravity, so you need to find how long each one takes to hit the ground using the kinematic equation for free fall, then subtract to find the time difference. Since both start from rest, the stone dropped from greater height will take longer—and the time to fall depends on the square root of the distance, not the distance itself.

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