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WAEC Physics 2025 Theory — Question 14

Question 14 of 34 from the West African Examinations Council (WAEC) Physics 2025 Theory paper, with the correct answer and a full explanation.

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9(c) A rubber gun is used to project a stone of mass 40g. If the rubber of the gun has an elastic constant of 350 Nm⁻¹ and was stretched 4 cm, calculate the stone's speed of projection.

Model answer

Elastic potential energy of the rubber = Kinetic energy of the stone: ½ke² = ½mv² → v = √(ke²/m) = √(350×(0.04)²/0.04) = √14 = 3.74 ms⁻¹.

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