Physics Help Forum Finding the mass of the planet
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 Oct 19th 2017, 06:18 PM #1 Junior Member   Join Date: Jun 2017 Posts: 15 Finding the mass of the planet Hi, I'm doing an independent course, so whenever I need help with a question it is very difficult to find it. The lesson I am on now has given me a question that I have no clue how to begin working on. Basically, a team of space explorers lands on a planet with a radius of 7.5*10^6 m. A 1kg mass on a spring scale measures 8.5N. I have to find the mass of the planet, and if an astronaut weighs more or less on that planet than Earth. I've gone back and forth through the lesson and I can't figure out my first step. There were no questions involving finding the mass of a planet so it is very confusing. I imagine we already know that a person weighs less on that planet than Earth because 1kg = 9.8N on Earth. Any help is much appreciated, Thanks
 Oct 19th 2017, 07:18 PM #2 Senior Member   Join Date: Apr 2017 Posts: 428 OK .... you need to find the mass of the planet , M .. you know the mass of the small weight m (1Kg) And you have force F (8.5) at the given radius r here's the formulae jpompey likes this. Last edited by oz93666; Oct 19th 2017 at 07:20 PM.
 Oct 19th 2017, 07:32 PM #3 Junior Member   Join Date: Jun 2017 Posts: 15 Wonderful, I figured it had to be that equation but wasn't thinking about the 1kg weight as the other object. Now I just have to solve for the mass of the planet. Thank you very much

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