CATAGORY: Mechanics QUESTION: How long would a 100W light bulb burn, on weighing 140g(if the mass was converted to energy)?

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Ah a good old E = mc^2 problem (here c^2 means c times c). Since energy (E) is power (P) times time (t) (1) E =Pt then (2) t = E/P Since here E = mass (m) times the speed of light (c) squared (3) E =mc^2 We can substitute (3) into (2) to give (4) t = mc^2/P m = 140g =.140kg c = 3 X 10^8 m/s P = 100W = 100J/s Thus (5) t = .140kg X (3 X 10^8 m/s)^2 / 100J/s = 1.26 X 10^14 seconds But there are 3.1536 X 10^7 seconds in one year so t = 1.26 X 10^14 s / 3.1536 X 10^7 s/yr = 3.995 X 10^6 years ************************ * t ~ 4 million years * ************************ ^ | | Impressive Eh?

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