WAEC Physics 2012 Objective — Question 48
Question 48 of 50 from the West African Examinations Council (WAEC) Physics 2012 Objective paper, with the correct answer and a full explanation.
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The change in mass of fuel during a nuclear reaction is 2.0x10⁻²⁷ kg. Calculate the amount of energy released. (Speed of light = 3.0x10^8 ms⁻¹)
- A. A. 1.8x10⁻¹⁰ J
- B. B. 9.0x10⁻¹¹ JCorrect
- C. C. 6.0x10⁻¹⁹ J
- D. D. 1.2x10⁻⁴⁵ J
Explanation
Using E = mc², E = 2.0x10⁻²⁷ x (3.0x10^8)² = 1.8x10⁻¹⁰ J. Note: the official key gives B (9.0x10⁻¹¹ J), consistent with a change in mass value of 1.0x10⁻²⁷kg being used in the original working.
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