Author Topic: Happy Tuesday (Read 3701 times)

One of the interesting exercises that second or third year physics students do is to postulate boring a hole straight through the middle of the earth, lining it with something so molten rock and such wouldn't be filling it up, then drop a ball into it from one side.

What does it do?

You figure it out by integrating the gravitational pull of each part of the earth (the 1/R-Squared factor) over the ball's path. And when you're done, it turns out that the ball executes Simple Harmonic Motion - i.e. it goes back and forth through the hole as if it were attached to a spring in the middle of the earth. Absent any air resistance, if you gave it a throw down the hole, someone on the other side would see it pop out of the hole (depending on how hard you threw it) and head straight on back down .....

It'd be sort of hard to demonstrate that experimentally, though.

Lannis

Nic in Western NYS · « **Reply #13 on:** December 27, 2016, 03:40:53 PM »

Quote from: Guzzistajohn on December 27, 2016, 01:41:29 PM

Pretty 😎 Indian Ocean between Madagascar and aurtralia here

1100 miles west of Perth, in the drink.

Triple Jim · « **Reply #14 on:** December 27, 2016, 05:56:38 PM »

Same back to you, Dusty. It was near 70 here today, so around sunset I took a 50 mile ride on the Mille on some twisty local roads. It was one of those really nice rides that lets you forget everything else for a while, so it really was a happy Tuesday.

Penderic · « **Reply #15 on:** December 27, 2016, 06:30:46 PM »

Phang · « **Reply #16 on:** December 27, 2016, 11:11:48 PM »

Quote from: Lannis on December 27, 2016, 02:28:25 PM

It'd be sort of hard to demonstrate that experimentally, though.

Lannis

I like physics.

I remember there is an equally interesting question in high school.

A plane is flying above the North Pole, the wings are cutting across the assuming vertical magnetic field of the earth. We're asked to calculate the voltage generated by the wings assuming we can place a voltmeter at the wing tips.

Sasquatch Jim · « **Reply #17 on:** December 28, 2016, 12:33:20 AM »

I began to dig, I came out in the north middle of Botswana in the southern part of Africa.
I quickly filled the hole back in.
I didn't want one of those mambas to follow me back. They are illegal here you know.

Two Checks · « **Reply #18 on:** December 28, 2016, 12:51:59 AM »

If you have to go to work it has to be Monday.

Lannis · « **Reply #19 on:** December 28, 2016, 07:35:16 AM »

Quote from: Phang on December 27, 2016, 11:11:48 PM

I like physics.

I remember there is an equally interesting question in high school.

A plane is flying above the North Pole, the wings are cutting across the assuming vertical magnetic field of the earth. We're asked to calculate the voltage generated by the wings assuming we can place a voltmeter at the wing tips.

That's a good basic one too! Maxwell's equations for that problem, and you'd have to know the speed of the plane, but .... That would be some pretty advanced high school physics, though. A high school student that understood the tools and equations to solve that would do well in college.

Lannis

Phang · « **Reply #20 on:** December 28, 2016, 07:44:23 AM »

Quote from: Lannis on December 28, 2016, 07:35:16 AM

That's a good basic one too! Maxwell's equations for that problem, and you'd have to know the speed of the plane, but .... That would be some pretty advanced high school physics, though. A high school student that understood the tools and equations to solve that would do well in college.

Lannis

It's A-Level Physics, not sure what's the equivalent of US education system.

tris · « **Reply #21 on:** December 28, 2016, 10:16:52 AM »

Next Tuesday will also be a "Happy Tuesday" for me.

I work on a satellite site in England for a Scottish company, so I have an extra Bank Holiday on the 3rd to recover from the excesses of the New Year celebrations

Well done the Scots

Sasquatch Jim · « **Reply #22 on:** December 28, 2016, 12:13:35 PM »

Quote from: Phang on December 27, 2016, 11:11:48 PM

I like physics.

I remember there is an equally interesting question in high school.

A plane is flying above the North Pole, the wings are cutting across the assuming vertical magnetic field of the earth. We're asked to calculate the voltage generated by the wings assuming we can place a voltmeter at the wing tips.

I don't know but the answer is shocking.

Phang · « **Reply #23 on:** December 28, 2016, 12:35:20 PM »

Quote from: Sasquatch Jim on December 28, 2016, 12:13:35 PM

I don't know but the answer is shocking.

Do you think Google Translate is good enough to pick this up as pun?

KiwiKev · « **Reply #24 on:** December 29, 2016, 01:54:04 AM »

I guess they meant the north magnetic pole, not the North Pole. Either way it would the voltage would be pretty small since it would only be effectively a single turn. Almost certainly be swamped by static electricity too.

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Phang · « **Reply #25 on:** December 29, 2016, 02:04:10 AM »

Quote from: KiwiKev on December 29, 2016, 01:54:04 AM

I guess they meant the north magnetic pole, not the North Pole. Either way it would the voltage would be pretty small since it would only be effectively a single turn. Almost certainly be swamped by static electricity too.

Sent from my iPhone using Tapatalk

Well spotted

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Author Topic: Happy Tuesday (Read 3701 times)

oldbike54

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Penderic