# Ball drop through earth

## Main Question or Discussion Point

If I drilled a hole all the way through the earth, and then dropped a ball down one end, what do you think the speed versus distance plot would look like?

I am interested in the centre point of the earth primarily - instinct tells me it would overshoot by quite a bit, but how far?

assume no wind resistance

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ZapperZ
Staff Emeritus
If I drilled a hole all the way through the earth, and then dropped a ball down one end, what do you think the speed versus distance plot would look like?

I am interested in the centre point of the earth primarily - instinct tells me it would overshoot by quite a bit, but how far?

assume no wind resistance
And if other assumptions to be made include the earth as a sphere with uniform density, no spinning, etc... then if you solve for the gauss's law equivalent for the gravitational field, you'll get a mass-spring system!

This is a common question in undergraduate mechanics course.

Zz