Universal Gratvitation Problems

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Homework Help Overview

The discussion revolves around problems related to universal gravitation, specifically addressing weight changes of objects at varying distances from the Earth's center and the implications of height on an astronaut's weight. Participants are exploring the gravitational force and its dependence on distance and mass.

Discussion Character

  • Exploratory, Assumption checking, Conceptual clarification

Approaches and Questions Raised

  • Participants discuss the relationship between weight and distance from the Earth's center, questioning how to determine the required distance for a specific weight change. There is also inquiry into the relevant equations that govern gravitational attraction.

Discussion Status

Some participants have begun to identify the relevant equations and ratios involved in the problems. There is an ongoing exploration of the concepts, with some expressing uncertainty about the equations and their applications. Guidance has been offered regarding the need to show work and clarify assumptions.

Contextual Notes

Participants are working under time constraints due to an upcoming test, which may influence their understanding and approach to the problems. There is mention of forum rules regarding homework help, emphasizing the need for participants to engage in the problem-solving process rather than receiving direct answers.

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1. An object weighing 90 N on the Earth's surface would weigh only 10 N when its distance from the center of the Earth is ____?



Do I solve for mass and try to find r?


2. An astronaut has a mass of 90 kg on the Earth's surface. If he moves to a height of 6 Earth radii above the Earth's surface, how much will be his weight?
 
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s-win said:
1. An object weighing 90 N on the Earth's surface would weigh only 10 N when its distance from the center of the Earth is ____?



Do I solve for mass and try to find r?


2. An astronaut has a mass of 90 kg on the Earth's surface. If he moves to a height of 6 Earth radii above the Earth's surface, how much will be his weight?

Welcome to the PF.

I fixed your post up a bit, and moved it to Intro Physics. The Advanced Physics forum is for upper-division and graduate-level questions.

When you fill out the Homework Help Template, take care to post your text between the bold lines you are given, instead of trying to replace that text with yours. The HH Template lines should stay visible and bold, and your text that you fill out should be plain text without any bolding.

When you fill out the HH Template, you list the Relevant Equations and your Attempt at a Solution.

What is the Relevant Equation for your first question? You don't need to solve for any mass -- the answer is independent of the mass of the object they are asking about...

Please show your work now...
 
I'm kinda lost since I only learned this lesson in less than an hour and I have a test tomorrow so... I don't know what equation to use?
 
s-win said:
I'm kinda lost since I only learned this lesson in less than an hour and I have a test tomorrow so... I don't know what equation to use?

What is the equation that relates the force of gravitational attraction to the mass of the Earth and the mass of the object and the distance separating their centers of mass? It's pretty much the only equation that applies, and I'm pretty confident you were shown in in the lesson. If not, check wikipedia.org ...

We do not give out answers here at the PF. The Rules link at the top of the page is pretty clear about how we handle Homework Help. Please show your work...
 
10N/90N = 1/9th of the force

1/9 = 1/r^2
 
s-win said:
10N/90N = 1/9th of the force

1/9 = 1/r^2

You are on the right track. Hopefully that means you found the right equation. So the ratio of the two radii is __________, which means that the object would be how far away?
 
3radii
 
s-win said:
3radii

Correct. Is that the form of the answer they want, or do they want a quantitative number?
 
berkeman said:
Correct. Is that the form of the answer they want, or do they want a quantitative number?

Just like that. I'm new to the website, what if I want to delete posts or adjust it to a different section?
 
  • #10
s-win said:
Just like that. I'm new to the website, what if I want to delete posts or adjust it to a different section?

Just click the Report button on your post and ask the Mentors to help. Ignore the messsage that says Reports are only for spam, etc. That's how you ask for help from the Mentors.

Keep in mind that we do not delete posts or threads that have replies.
 

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