World Jump Day

[Thomas Wood]

Hey its my first post,so be nice.

 

 

Have anybody here heard of 'world jump day'.

 

The guy claims that iff 600 milion people jump simultaneously the worlds orbit will change .....

 

What's your opinion?

 

World Jump Day

[swansont]

Hey its my first post' date='so be nice.

 

 

Have anybody here heard of 'world jump day'.

 

The guy claims that iff 600 milion people jump simultaneously the worlds orbit will change .....

 

What's your opinion?

 

World Jump Day

 

It's an internal force, so you can't use it to change the linear momentum of the system. The center-of-mass can't move. Further, the mass of those people (~6 x 10¹⁰ kg) is insignificant compared to the mass of the earth (6 x 10²⁴kg), so the earth won't move much anyway. And if the people are distributed symmetrically, there's no earth motion at all in that frame.

 

 

I am of the opinion that "the guy" doesn't know much physics.

[Johnny5]

It's an internal force' date=' so you can't use it to change the linear momentum of the system. The center-of-mass can't move. Further, the mass of those people (~6 x 10[sup']10[/sup] kg) is insignificant compared to the mass of the earth (6 x 10²⁴kg), so the earth won't move much anyway. And if the people are distributed symmetrically, there's no earth motion at all in that frame.

 

 

I am of the opinion that "the guy" doesn't know much physics.

 

Yes, the center of mass of earth+inhabitants will continue in its roughly elliptical path, as if they had never jumped. The earth will buck slightly one way, but for all intent and purpose, the earth can be considered infinitely massive compared to the mass of the people, and they can jump up and down all they want, there will be no effect which is measurable.

[ed84c]

Hey its my first post' date='so be nice.

 

 

Have anybody here heard of 'world jump day'.

 

The guy claims that iff 600 milion people jump simultaneously the worlds orbit will change .....

 

What's your opinion?

 

World Jump Day

 

Its a good job you asked us to 'be nice'......lol

[ed84c]

Imagine jumping, australians will be jumping the oposite direction to the americans.

 

Hmm its a bit like the film where too many nuclear tests, have the same affect, but that was BS as well.

[Thomas Wood]

lol

 

yeah i thought it was bs too,just wanted expert opinions

[crazybean]

I'm laughing. 'The Guy' truly is hilarious! I signed up to make sure he doesn't feel sad and I hope you will too. Remember, for every person who signs up to this, no difference can be made to the state of the Earth, but it will make one sad man generally more happy.

[Thomas Wood]

yes, i joined, and will jump, not sure why though...

[Skye]

This idea was tried maybe ten years ago here, the idea that if everyone jumped up and down at the same time it might have some measurable effect. It didn't work. It's obviously not going to work if people all over the place do it at the same time.

[swansont]

This idea was tried maybe ten years ago here, the idea that if everyone jumped up and down at the same time it might have some measurable effect. It didn't work. It's obviously not going to work if people all over the place do it at the same time.

 

I think I showed that it's not going to work, period, as far as changing the orbit goes.

 

As far as "some measurable effect" like jumping on a fault line in hopes of triggering an earthquake, I am not qualified to assess that.

 

I meantioned in another thread that getting everyone into their cars (or on a bike, if they don't have a car) and driving East (or West) should measurably change the earth's rotation rate.

[Thomas Wood]

cool, so what your saying is we could make days longer or shorter?

[swansont]

Temporarily. The earth would slow down or speed up, then go back to normal. There wouldn't be a permanent change, but there would be an accumulated time difference, like setting your watch a minute fast, and then its rate was perfect from then on. But you need to realize what "measurable" is - I'm talking atomic clock precision here.

 

The earth's rotational angular momentum is (assuming I did the math right) about 7 x 10³³ kgm^2/s (I assumed uniform density. Since the core is actually more dense, the real number should be smaller). A billion people in cars at 1000 kg moving at 20 m/s (about 40 mph) has an angular momentum of about 6.4 x 10¹⁹ (being on the surface is a big advantage here), so the rotational rate changes by about 2 parts in 10¹⁴. If they drove all day, they'd add or subtract a nanosecond to/from the rotation. If they loaded up their pickps and SUVs with stuff, they'd change it more.

[Guest nasza]

That sound cool. My day is way do short!