What is the gravity of a planet 2 times the radius and 3 times the mass of earth

AI Thread Summary
The discussion centers on calculating the gravity of a hypothetical planet with twice the radius and three times the mass of Earth. A user is attempting to determine the weight of a person who weighs 540N on Earth using the gravitational force equation. They initially struggle with the calculations and express confusion over the correct application of the formula. Clarification is sought regarding the proper use of the radius in the equation. Ultimately, the user arrives at a calculated weight of approximately 793.18N for the person on the new planet.
cmbswim89
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what is the gravity of a planet 2 times the radius and 3 times the mass of earth
 
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cmbswim89 said:
what is the gravity of a planet 2 times the radius and 3 times the mass of earth
Hello cmbswim89. Welcome to PF !

Do you mean, "What is the acceleration due to gravity on the surface of a planet 2 times the radius and 3 times the mass of earth?"

Show us what you have tried, and where you're stuck so we can help you.
 


well the problem states a person weighs 540N on Earth and asks how much he weighs on a planet 2 times the radius and 3 times the mass. i have tried putting that data into the gravitational force equation but multiplying Earth's mass by 3 and radius by 2 but i don't get any of the multiple choice questions i have
 


cmbswim89 said:
well the problem states a person weighs 540N on Earth and asks how much he weighs on a planet 2 times the radius and 3 times the mass. i have tried putting that data into the gravitational force equation but multiplying Earth's mass by 3 and radius by 2 but i don't get any of the multiple choice questions i have
What equation are you putting the mass & radius into ?

What do you get?
 


F=G(3(m1))(m2)/2r2 so it looks like that with m1 as Earth's mass and r as Earth's radius and i get 793.18N
 


cmbswim89 said:
F=G(3(m1))(m2)/2r2 so it looks like that with m1 as Earth's mass and r as Earth's radius and i get 793.18N

Are you using (2r)2 or 2(r2) in the denominator?
 
sr^2 sorry
 

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