m = 400 g = 0.4 kg.
g = 9.8 m / s ^ 2.
h = 12 m.
Mechanical work A is determined by the formula: A = F * S * cosα, where F is the force under the action of which the work is performed, S is the displacement under the action of the force, α is the angle between the force and the displacement.
Gravity acts on the stone: F = m * g.
The movement is equal to the height from which the stone falls: S = h.
Angle α = 0, this is the angle between gravity m * g and displacement h.
cos0 = 1.
A = m * g * h.
A = 0.4 kg * 9.8 m / s ^ 2 * 12 m = 47.04 J.
Answer: gravity does the work A = 47.04 J.
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