Six terms . One for when the second particle is brought in.
Two for then the third particle is brought in. Three for when the third particle is brought in.
You could also think of it as 12 QiQj/Rij pairs, but they occur in six equal pairs, and must not be double-counted.
a system consists of four particles how many terms appear in the expression for the total gravitational potential energy of the system
2 answers
This answer is correct. However, there is a back-story. Each of the four exerts a gravitational force on the others. As the distance between them approaches infinity, that value of that force approaches zero. Initially, one particle points to the other three. Three terms. Remove one as it approaches infinite distance. You are left with one pointing to two. Add two. Finally, you have one pointing to the other. Add one. Total is six terms.
1 answer