Gravitation

Gravitation Problem on Gravitation Rate Topic:

#1 12 February 2012 - 05:36 PM Avirup-Croocked Scientist

Lepton

Hello friends,
I would appreciate your thankful help in solving this problem on gravitation from an IIT practice paper:-
A tunnel is dug in the earth across one of its diameter. Two masses m and 2m are dropped from the ends of the tunnel. The masses collide and stick to each other and perform SHM. Then amplitude of SHM will be (when R=radius of the earth)
(a) R (b) R/2 © R/root3 (d) 2R/3.
I will be pleased if anyone writes the concept used and explains the steps briefly........ a fresher to the `SFN` looking forward to a reply soon.
Thanking You

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#2 13 February 2012 - 01:30 AM mathematic

Atom

What are SHM and SFN?

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#3 13 February 2012 - 02:05 AM D H

Physics Expert

SHM = simple harmonic motion.
SFN = ScienceForums.net

Avirup-Croocked Scientist, what work have you done on this problem? This is essentially a homework problem. You need to show some work before we can help you.

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#4 13 February 2012 - 02:53 AM DrRocket

Primate

Avirup-Croocked Scientist, on 12 February 2012 - 05:36 PM, said:

Concepts to be used:

1) Newtonian gravity $F=G \frac {m_1m_2}{r^2}$

2) Classical Newtonian mechanics $F=ma$

But as DH said, you need to show some work and a reasonable attempt to use these principles.

You can know the name of a bird in all the languages of the world, but when you're finished, you'll know absolutely nothing whatever about the bird... -- Richard P. Feynman

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#5 14 February 2012 - 06:19 PM elfmotat

Meson

Are you familiar with Gauss' Law for electric fields? There's also a Gauss' law for gravitational fields:

$\oint\boldsymbol{g}\cdot d\boldsymbol{A}=-4\pi GM$

**Hint: In a typical E&M class you'll eventually be asked to solve for the electric field in the interior of a sphere with constant charge density (E as a function of the distance from the center).

This post has been edited by elfmotat: 14 February 2012 - 06:19 PM