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Old Apr 28th 2012, 10:14 AM   #1
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Question conservation of angular momentum

Consider an Earth-like planet hit by an aster-
oid.
The planet has mass Mp= 2.87 ◊ 1023kg
and radius Rp= 5.44 ◊ 106m, and you may
approximate it as a solid ball of uniform
density.
It rotates on its axis once every
T = 13 hr.
The asteroid has mass Ma =
1.82 ◊ 1017kg and speed va = 38400 m/s
(relative to the planetís center); its velocity
vector points θ = 66◦below the Eastward hor-
izontal. The impact happens at an equatorial
location.

The impact is totally inelastic ó the asteroid
is stuck in the planetís crust. But thanks to
the asteroidís angular momentum, the planet
rotates faster after the impact than it did
before.
By how many seconds has the collision
shortened the planetary day?
For simplicity, ignore the effect of the aster-
oidís mass on the planetís moment of inertia
and assume
Iafter= Ibefore
planet.
Warning: At intermediate stages of this cal-
culation, do not round off intermediate results
and keep at least 7 significant digits. answer in units of second
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Old Apr 28th 2012, 10:16 AM   #2
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please help. i tried every possible thing i could but cannot get the answer.
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Old Apr 28th 2012, 11:49 AM   #3
Pmb
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Originally Posted by amirshrestha View Post
please help. i tried every possible thing i could but cannot get the answer.
Forum rules prohibit us against posting answers in full without an attempt by yourself. You said that you tried every possible thing you could. If so then simply post one of those attempts here verbatim so that we know that you have some idea of how to attempt an answer. We have to know that you're not simply posting a question here and writing the answer in as your homework answer.
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