Most geologists believe that the dinosaurs became extinct 65 million years ago w

Question

Most geologists believe that the dinosaurs became extinct 65 million years ago when a large comet or asteroid struck the earth, throwing up so much dust that the sun was blocked out for a period of many months. Suppose an asteroid with a diameter of 2.0 km and a mass of 5.00 1012 kg hits the earth with an impact speed of 5.00 104 m/s.
(a) What is the earth's recoil speed after such a collision? (Use a reference frame in which the earth was initially at rest.)
m/s

(b) What percentage is this of the earth's speed around the sun? (Use 1.50 1011 m as the mean distance from the earth to the sun.)
%

(c) How much kinetic energy was "released" (converted to thermal and other forms of energy) in this collision? [For comparison, the Hiroshima atomic bomb released about 5 x 1013 J].
J

Explanation / Answer

?P = 0 M V + m v - (M + m) v' = 0 M (0) + (10^13)(4 * 10^4) - (5.97 * 10^24 + 4 * 10^4) v' = 0 v' = 6.7 10^(-8) m/s (b). Average earth's orbital speed = 29.783 km/s v' just 2.25 * 10^(-10) % of earth's orbital speed

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