sol invictus
Philosopher
- Joined
- Oct 21, 2007
- Messages
- 8,613
This looks pretty good:
http://galileo.phys.virginia.edu/classes/152.mf1i.spring02/GravField.htm
I recommend you read the section on superposition and just below. For instance:
"Note that the force is exactly zero at the origin, and everywhere else it points towards the origin."
Even better:
"Field Inside a Spherical Shell
This turns out to be surprisingly simple! We imagine the shell to be very thin, with a mass density kg per square meter of surface. Begin by drawing a two-way cone radiating out from the point P, so that it includes two small areas of the shell on opposite sides: these two areas will exert gravitational attraction on a mass at P in opposite directions. It turns out that they exactly cancel. "
http://galileo.phys.virginia.edu/classes/152.mf1i.spring02/GravField.htm
I recommend you read the section on superposition and just below. For instance:
"Note that the force is exactly zero at the origin, and everywhere else it points towards the origin."
Even better:
"Field Inside a Spherical Shell
This turns out to be surprisingly simple! We imagine the shell to be very thin, with a mass density kg per square meter of surface. Begin by drawing a two-way cone radiating out from the point P, so that it includes two small areas of the shell on opposite sides: these two areas will exert gravitational attraction on a mass at P in opposite directions. It turns out that they exactly cancel. "
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