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

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

SammyS
Staff Emeritus
Homework Helper
Gold Member

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 earths mass by 3 and radius by 2 but i don't get any of the multiple choice questions i have

SammyS
Staff Emeritus
Homework Helper
Gold Member

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 earths 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 earths mass and r as earths radius and i get 793.18N

SammyS
Staff Emeritus