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Kinetic Energy of an NEA Impact Event

This article explores the amount of kinetic energy released when a meteorite hits the Earth, using the formula K.E. = 0.5mv2. It also compares this energy to real-world equivalents, such as U.S. energy consumption and the Hiroshima atomic bomb.

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Kinetic Energy of an NEA Impact Event

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  1. Kinetic Energy of an NEA Impact Event Contributed by Eric B. Grosfils Pomona College

  2. How Much “Whack” Could An ImpactPack If An Impact Did Smack Earth? QUESTION 1 When a meteorite hits the Earth, how much kinetic energy is released? K.E. = 0.5 mv2 (m is mass in kg, v is velocity in m/s, K.E. in Joules) Assume the impactor is spherical, 6 m in diameter, with a density of 3.5 g/cm3 (3500 kg/m3) Mass is ~4 x 105 kg (~430 tons)

  3. SUB - QUESTION What velocity should we use? Min: 11.2 km/s Earth’s Escape Velocity Starts at 0.0 km/s Very far apart! Hits at 11.2 km/s

  4. SUB - QUESTION What velocity should we use? Max: 42.0 km/s Escape Velocity from Sun + 30.0 km/s Orbital Velocity of the Earth 72.0 km/s Average: 15-25 km/s for asteroids Let’s use a velocity of 20 km/s 30 km/s 42 km/s

  5. QUESTION 1 When a meteorite hits the Earth, how much kinetic energy is released? K.E. = 0.5 * (4 * 105) * (20,000)2 K.E. is ~8 x 1013 J and that means… ? 

  6. QUESTION 2 In “real terms” how much energy is this really? ? U.S. Consumption per year in late 1990’s was ~100 quadrillion btu = 1020 J (Impact energy would power US for ~30 seconds) – or –

  7. Another way to look at it… Hiroshima atomic bomb released ~8 x 1013 J Mushroom cloud over Hiroshima rising 18 km into the air ; August 6 1945 http://www.atomicarchive.com/Photos/Hiroshima/image1.shtml

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