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

2. How Much “Whack” Could An Impact Pack If An Impact Did Smack Earth? QUESTION 1 When a meteorite hits the Earth, how much kinetic energy is released? K.E. = 0.5 mv 2 (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/cm 3 (3500 kg/m 3 ) Mass is ~4 x 10 5 kg (~430 tons)

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

4. SUB - QUESTION What velocity should we use? Max:42.0 km/sEscape Velocity from Sun + 30.0 km/sOrbital 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/s42 km/s

5. QUESTION 1 When a meteorite hits the Earth, how much kinetic energy is released? K.E. = 0.5 * (4 * 10 5 ) * (20,000) 2 K.E. is ~8 x 10 13 J and that means… ? 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 = 10 20 J (Impact energy would power US for ~30 seconds) – or –

7. Another way to look at it… Hiroshima atomic bomb released ~8 x 10 13 J Mushroom cloud over Hiroshima rising 18 km into the air ; August 6 1945 http://www.atomicarchive.com/Photos/Hiroshima/image1.shtml