Uploaded January 2026 | Updated September 2026, 3 weeks ago

---

Just a cool thought experiment. If you drilled a hole straight through the earth, how long would it take a ball dropped in one side to come out the other. How fast would it be going?

Let's do some interesting math and learn some things about harmonic motion (the ball would go back and forth between the openings like a harmonic oscillator or a spring/pendulum). Then we have a couple of surprises from the math...

Here is the discord link:
discord.gg/yPUgFMSpZ7

Join this channel to get access to perks:
youtube.com/channel/UC68chxz-bc3e1gYq5WdfClA/join

Donate to the Telescope Fund:
patreon.com/posts/116418109
MEMBERSHIPS: patreon.com/c/bobthescienceguy/membership
PayPal Link Telescope Link: paypal.com/donate/?hosted_button_id=JSAFP8KSRZDQQ

Bob's Websites
Check them OUT:

Bob the Science Guy: youtube.com/user/drbob420

ResearchFlatMoon (the production channel):
youtube.com/c/ResearchFlatMoon

Slide Rules and Mathematics (STEM Education):
youtube.com/channel/UCEXa89aIdG222z8ADB0e7GA

Shamrock Banks Observatory:
youtube.com/c/CommonSenseScience

Please consider becoming a Patreon of the Channel- All money donated through paypal or from the patreons goes directly into improvements in the channel (computers, cameras, lights etc) or to create educational videos (sextants, telescope equipment, etc).

patreon.com/bobthescienceguy

Bob