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Natural Science Forum / Physics / General Physics / July 2008Question about terminal velocity
Assume an asteroid is traveling at 25,000 mph on on collision course with the Earth----and is one million miles away. When that asteroid gets close enough for the Earth's gravitational field to exert a strong influence will the asteroid accellerate to an even higher velocity prior to impact? IOW, everything being relative, why won't the Earth's gravitation "add" 25,000 mph more in velocity for an impact speed of 50,000 mph. If you believe the asteroid would 'accellerate' [sic], you would have to believe the Earth's gravity affects other bodies, you blithering Google-posting AOL-using twat. > My brain fit in gnat bung-hole! > If you believe the asteroid would 'accellerate' [sic], > you would have to believe the Earth's gravity [quoted text clipped - 4 lines] > > - Show quoted text - Oh, you caught me in a misspelling, how tremendously clever of you. Actually I know the answer and it is not what you think. I Which do you believe? Pick one only: 1) The Earth's gravity affects nearby masses. 2) The Earth's gravity does not affect nearby masses. > Which do you believe? Pick one only: > > 1) The Earth's gravity affects nearby masses. > > 2) The Earth's gravity does not affect nearby masses. 3) The gravity of the situation does not affect idiots. Hey stooopid - gravity affects up to surface objects, gravitation affects everything else outward. Now factor in quadrupole corrections for the radially divergent gravitational field. Idiot.  SignatureUncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/lajos.htm#a2 Uncle Al If not for Earths gravity we would not have flat feet. Its action at a distance gave Earth its nice Moon. If not for Earths gravity man would not have invented wine. If not for earth gravity how would we squeeze the grape. Bert > Assume an asteroid is traveling at 25,000 mph on on collision course > with the Earth----and is one million miles away. Earth has a mean orbital velocity of 29.8 km/s and an equatorial diameter of 12,756 km. Earth passs through its own diameter every 7.13 minutes. Slow or speed the asteroid by 0.3%, 75 mph. > When that asteroid > gets close enough for the Earth's gravitational field to exert a > strong influence will the asteroid accellerate to an even higher > velocity prior to impact? Add escape velocity, 11.2 km/sec. > IOW, everything being relative, why won't the Earth's gravitation > "add" 25,000 mph more in velocity for an impact speed of 50,000 mph. v = at a = GM/r^2 Integrate for changing acceleration with radial separation to get average velocity at a given radius. SignatureUncle Al http://www.mazepath.com/uncleal/ (Toxic URL! Unsafe for children and most mammals) http://www.mazepath.com/uncleal/lajos.htm#a2 > Assume an asteroid is traveling at 25,000 mph on on collision course > with the Earth----and is one million miles away. When that asteroid [quoted text clipped - 3 lines] > IOW, everything being relative, why won't the Earth's gravitation > "add" 25,000 mph more in velocity for an impact speed of 50,000 mph. You mean escape velocity. Terminal velocity is the velocity at which friction equals gravity, and objects no longer accelerate. Earth's gravitation would add (1/2)*(the asteroid mass)*(25,000 mph)^2 to the kinetic energy of the asteroid. (25,000 mph is Earth's escape velocity.) Assuming that the original 25,000 mph is relative to the Earth's motion, so that we don't have to account for orbital velocity too, you'd get an impact speed of sqrt(2)*(25,000 mph) or about 35,000 mph. SignatureJim E. Black (domain in headers) How to filter out stupid arguments in 40tude Dialog: !markread,ignore From "Name" +"<email address>" [X] Watch/Ignore works on subthreads Osm It does add speed. The 25,000 mph is just an estimate impact average. Some asteroid land with little impact. Bert |
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