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Question
(a) On a particular day, it takes $9.60\times 10^{3}\textrm{ J}$ of electric energy to start a truck’s engine. Calculate the capacitance of a capacitor that could store that amount of energy at 12.0 V. (b) What is unreasonable about this result? (c) Which assumptions are responsible?
1. $133\textrm{ F}$
2. A capacitor of this capacitance would be so massive and heavy that a truck would not be able to carry it. If we assumed the capacitor is a parallel plate capacitor with the highest capacity dielectric, strontium titanate, with square plates, the side length of the square would be 254 km!
3. It's unreasonable to presume this energy could be supplied by a capacitor. Batteries are used instead.
Solution Video