# Circular Motion & Universal Gravitation: Gravity Between

1. Nov 25, 2008

### cocobandit13

1. The problem statement, all variables and given/known data

Two "swarms" of krill each contain 1.200×107 identical individuals. The centers of gravity of the "swarms" are 15.0 meters apart. By what factor will the gravitational force of attraction between the two "swarms" change, if 9.231×106 new krill join each "swarm?"

Use the Law of Universal Gravitation and proportional reasoning. Also, remember that any individual factor of change is simply the new value divided by the old value. A factor is the number you must multiply your old value by to get your new value.

2. By what factor will the gravitational force of attraction between the two original "swarms" change, if 9.231×106 krill move from one swarm to the other?

Use the Law of Universal Gravitation and proportional reasoning

3.By what factor will the gravitational force of attraction between the two original "swarms" change, if 1.080×107 new krill join each "swarm", and the swarms move until they are 6.52 meters apart?

Use the Law of Universal Gravitation and proportional reasoning

4.By what factor will the gravitational force of attraction between the two original "swarms" change, if the swarms drift to 45.00 meters apart?

Use the Law of Universal Gravitation and proportional reasoning

2. Relevant equations
F=G(m1m2/r^2)
G=6.67x10^-11
F=ma
a=v^2/r
a=4pi^2r/T^2
T=period or time
etc...

3. The attempt at a solution
no attempts

2. Nov 26, 2008

### LowlyPion

Welcome to PF.

How would you think to start?

For instance by what percentage does the effective mass of a swarm increase?