• Support PF! Buy your school textbooks, materials and every day products Here!

Newton's law of gravitation

  • Thread starter Calpalned
  • Start date
  • #1
297
6
1. The problem statement, all variables and given/known
according
to my calculus III textbook, the gravitational force acting on an object at ##x = <x,y,z>## is ##F(x)=-\frac{mMG}{|x|^3} x ##. What's the point of having a cube on the bottom. Why shouldn't I memorize it as ##F(x)=-\frac{mMG}{|x|^2} ##

Homework Equations


See above

The Attempt at a Solution

 

Answers and Replies

  • #2
297
6
1. The problem statement, all variables and given/known
according
to my calculus III textbook, the gravitational force acting on an object at ##x = <x,y,z>## is ##F(x)=-\frac{mMG}{|x|^3} x ##. What's the point of having a cube on the bottom. Why shouldn't I memorize it as ##F(x)=-\frac{mMG}{|x|^2} ##

Homework Equations


See above

The Attempt at a Solution

IMG_5063.JPG
 
  • #3
gneill
Mentor
20,718
2,715
x is a vector. ##G\frac{M m}{|\mathbf{x}|^2}## is the magnitude of the force, while ##\frac{\mathbf{x}}{|\mathbf{x}|}## is a unit vector in the direction of the force.
 

Related Threads for: Newton's law of gravitation

  • Last Post
Replies
1
Views
774
  • Last Post
Replies
3
Views
7K
  • Last Post
Replies
1
Views
934
  • Last Post
Replies
2
Views
4K
  • Last Post
Replies
5
Views
2K
  • Last Post
Replies
13
Views
2K
Replies
7
Views
6K
  • Last Post
Replies
2
Views
1K
Top