Question

It has been suggested, and not facetiously, that life might have originated on Mars and been carried to
Earth when a meteor hit Mars and blasted pieces of rock (perhaps containing primitive life) free of the
surface. Astronomers know that many Martian rocks have come to Earth the way. (For information
on one of these, search the Internet for ”ALH 84001”. One objection to this idea is that microbes
would have to undergo an enormous, lethal acceleration during the impact. Let us investigate how
large such an acceleration might be. To escape Mars, rock fragments would have to reach its escape
velocity of 5.0 kilometers per second, and this would most likely happen over a distance of about 4.0
meters during the impact.
(a) What would be the acceleration, in meters per second squared and g’s, of such a rock fragment?
(b) How long would this acceleration last?
(c) In tests, scientists have found over 40% of Bacillus subtilis bacteria survived after an acceleration
of 450, 000g. In light of your answer to part (a), can we rule out the hypothesis that life might
have been blasted from Mars to Earth?

Answer 1

vf^2=vi^2+2ad
5000^2=0+2a*4

a=5000^2/8

for time:
vf=at solve for time t.