WAEC Physics 2017 Objective — Question 12
Question 12 of 50 from the West African Examinations Council (WAEC) Physics 2017 Objective paper, with the correct answer and a full explanation.
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A vertical string, suspended from a fixed point and having a small mass attached to the free end, is set into oscillations. Which of the following statements about the system are correct? I. The potential energy of the mass is minimum at the middle of the swing. II. Its kinetic energy is maximum at the middle of the swing. III. The sum of the potential and kinetic energies is constant throughout the swing.
- A. A. I, II and IIICorrect
- B. B. I and II only
- C. C. II and III only
- D. D. I and III only
Explanation
At the middle (equilibrium point) of the swing, PE is minimum and KE is maximum. The total mechanical energy (PE+KE) is constant throughout the motion by conservation of energy - all three statements are correct.
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