You serve on a asteroid-watch station when the computer
reports that as a result of the current passage of Mars, one of the
earth-
orbit crossing asteroids with a known mass of m = 4 1013
tons,
changed orbit and is now on a course of direct collision with
earth. To
assess the situation you bounce a radar signal to the
asteroid.
(a) What is the distance to the asteroid if the signal returns for
36
seconds?
(b) Your radar operates at frequency of f0 = 20 GHz (wavelength of
1.5
cm), the received back signal has a wavelength of = 1.49988 cm.
What
is the speed of the asteroid?
(c) How many hours remain until the collision?
(d) What is the kinetic energy of the asteroid?