Exam-style question
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Which equation correctly represents the mass‑energy equivalence principle?.
- A.E = mc^2
- B.E = 1/2 mv^2
- C.E = mgh
- D.E = kx^2
Model answer
What a good answer should say
- E = mc^2
Explanation
Why this works
Formula/rule: E = mc^2, where E is energy, m is mass and c is the speed of light. Substitution: for a mass of 1 kg, c = 3.0×10^8 m s⁻¹.
Working: E = 1 kg × (3.0×10^8 m s⁻¹)² = 9.0×10^16 J. Answer: 9.0×10^16 J.
Units/conclusion: The equation shows that mass can be converted into a large amount of energy, expressing the mass‑energy equivalence principle.
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