what is the gravitation force at the core of the earth crust. say i have dug a hole through the core from one pole of the earth to the other. neglecting the pressure and temperature, what will happen to an object dropped in that hole.
will it stop at the centre or come out at the other end.?
The object will execute a simple harmonic motion, i.e. it will oscillate to and fro along the imaginary tunnel inside the earth. If you want to know more details about such oscillation and its period of motion, you may refer to Fundamentals of physics (Halliday, 5th - 7th edition), it will give you a clear idea and detailed calculation.
Hope the above will give a little help.
the gravity at the centre of the earth would be zero....
and it can proved that an object dropped by digging a hole from end to end of the earth would execute simple harmonic motion...
When you first drop the object, it will have a certain potential energy. The object will oscillate from one side to the other as stated above. However, as the object moves through the air it will encounter friction which will turn to heat and gradually reduce the potential energy. At some point it will come to rest at the center.
I agree with you all. The only definition I would change is that the gravity at the center would not be zero it would be uniformly equal in all directions leaving the object floating in the middle of the gravity field.