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What happens to your kinetic energy if you increase your speed from 30 km/h to 90 km/h?
“Kinetic energy increases quadratically with increasing speed” (Du och jag i trafiken, körkortsbok / teoribok [You and me in traffic], 28th Edition, page 159)
How many times faster is the speed? 90 / 30 = 3, i.e. the speed is 3 times faster.
How many times greater is the kinetic energy? 32 = 3*3 = 9, i.e. the kinetic energy is 9 times greater.
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