# Electric Charges

1. Jul 9, 2012

### CombatVetUSMC

1. The problem statement, all variables and given/known data
An electrically neutral model airplane is flying in a horizontal circle on a 2.5-m guideline, which is nearly parallel to the ground. The line breaks when the kinetic energy of the plane is 50 J. Reconsider the same situation, except that now there is a point charge of +q on the plane and a point charge of -q at the other end of the guideline. In this case, the line breaks when the kinetic energy of the plane is 51.5 J. Find the magnitude of the charges.

2. Relevant equations
T$_{}max$ = 2*KE$_{}1$/r
F= F$_{}c2$ - T$_{}max$
q=√Fr$^{}2$/k

3. The attempt at a solution
T$_{}max$= 2(50J)/2.5m= 40J/m

not sure how to get F$_{}c2$
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Jul 10, 2012

### tiny-tim

Welcome to PF!

Hi CombatVetUSMC! Welcome to PF!