A 0.3 kg marble is dropped from 2 m. If air resistance is negligible, what speed does it reach just before impact? Use v^2 = 2 g h.

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Multiple Choice

A 0.3 kg marble is dropped from 2 m. If air resistance is negligible, what speed does it reach just before impact? Use v^2 = 2 g h.

When air resistance is neglected, gravitational potential energy lost during the fall becomes kinetic energy gained. This means m g h = 1/2 m v^2, so the mass cancels and v^2 = 2 g h. With g ≈ 9.8 m/s^2 and h = 2 m, v^2 = 2 × 9.8 × 2 = 39.2, so v = √39.2 ≈ 6.26 m/s. The speed depends only on height (not the mass) in this ideal case, and this calculation gives the correct impact speed.

When air resistance is neglected, gravitational potential energy lost during the fall becomes kinetic energy gained. This means m g h = 1/2 m v^2, so the mass cancels and v^2 = 2 g h. With g ≈ 9.8 m/s^2 and h = 2 m, v^2 = 2 × 9.8 × 2 = 39.2, so v = √39.2 ≈ 6.26 m/s. The speed depends only on height (not the mass) in this ideal case, and this calculation gives the correct impact speed.

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