Naked Science Forum

General Discussion & Feedback => Radio Show & Podcast Feedback => Topic started by: macFanDave on 18/10/2005 19:25:44

Title: Jupiter gravity.
Post by: macFanDave on 18/10/2005 19:25:44

I've always learned that the force of gravity on the surface of Jupiter is about 2-1/2 times what it is on the surface of Earth.

A 50 kg person "weighs" about 500 N (newtons) on Earth and would weigh about 1250 N on Jupiter.

Jupiter has about 318 times the mass of Earth and its radius is about 11 times larger.

I think your mistake is saying that one's weight is proportional to the product of the masses of the bodies (the person and the planet), but that is only half the story.  According to Newton's Law of Gravity, the force of gravity between two bodies is ALSO inversely proportional to the square of the distances between their centers.

If you calculate 318/(11^2), you get about the factor of 2-1/2 I mentioned earlier.  I think I am right, but please straighten me out in case I am wrong.

Love the show.

Dave
Houston, Texas

Title: Re: Jupiter gravity.
Post by: daveshorts on 25/10/2005 19:36:29

That sounds about right to me, which show was it?

Title: Re: Jupiter gravity.
Post by: chris on 26/10/2005 08:39:44

I'll have to look into this because I didn't write that Fact or Fiction - Catherine did.

Thanks for highlighting it. I'll come back to you.

Chris

"I never forget a face, but in your case I'll make an exception"
 - Groucho Marx

Title: Re: Jupiter gravity.
Post by: Dr B on 18/01/2006 17:06:24

MacFanDave's calculation is correct.  

I think you got your units mixed up on the show.  On Earth the 50kg person weighs 500 Newton's and on Jupiter about 1300 Newtons.  

However I am not sure how you could stand on the surface of Jupiter - it is not solid

Dr B
Istanbul

Title: Re: Jupiter gravity.
Post by: DoctorBeaver on 20/01/2006 03:52:21

Simon - I believe there is evidence to show that Jupiter does have a solid core. I'll try to find a reference.

Title: Re: Jupiter gravity.
Post by: DoctorBeaver on 20/01/2006 03:53:44

That didn't take long!

http://stardate.org/resources/ssguide/jupiter.html

Title: Re: Jupiter gravity.
Post by: Dr B on 20/01/2006 05:48:27

I guess if you were standing on the solid surface I would have to think again about calculating the gravitational acceleration at that point!  You would be inside the planet ...

Dr B
Istanbul