Is my book wrong or am I?

  • Thread starter bcjochim07
  • Start date
  • #1
374
0

Homework Statement


Find the total gravitational potential energy of the three masses.


Homework Equations


U=-GMm/r


The Attempt at a Solution



U between the 10 kg mass & the 20kg mass
-(6.67*10^-11)(20kg)(10kg)/.20 m = -6.67 * 10 ^-8 J

U between the 20kg mass and the 5 kg mass
-(6.67*10^-11)(20kg)(5kg)/.10m = -6.67*10^-8 J

U between the 10 kg mass & the 5 kg mass
-(6.67*10^-11)(10kg)(5kg)/.2236 m = -1.49 * 10^-8 J

adding them up I got -1.483*10^-7 J

but the back of my book says -1.96 * 10^-7 J

Am I doing something wrong?
 

Attachments

  • amasses.jpg
    amasses.jpg
    5.2 KB · Views: 1,136

Answers and Replies

  • #2
alphysicist
Homework Helper
2,238
2
Hi bcjochim07,

The image file is not ready to view. Is it simple enough to describe in words?
 
  • #3
374
0
A 10 kg mass is located 20 cm directly above a 20 kg mass. And 10 cm to the right of the 20kg mass is a 5kg mass. The masses form a right angle
 
  • #4
alphysicist
Homework Helper
2,238
2
Your answer looks right to me.
 

Related Threads on Is my book wrong or am I?

Replies
3
Views
3K
  • Last Post
Replies
7
Views
2K
  • Last Post
Replies
7
Views
2K
  • Last Post
Replies
5
Views
9K
  • Last Post
Replies
15
Views
2K
Replies
12
Views
2K
  • Last Post
Replies
4
Views
1K
Top