A 4.0 m long thin rod is pinned so that it spins about its center. The rod has a rotational inertia of 8.0 kg m2 about this center. The rod has two 3.0 kg masses attached at each end. What force F must be applied to one end to make the system rotate with an angular acceleration of 4.0 rad/s2 about its center

a charge 3q is at the origin, and a charge −2q is on the positive x axis at x=a. part a where on the x-axis would you place a third charge so it would experience no net electric force? enter an expression for the exact answer, which will involve a square-root sign. (do not enter an approximate decimal answer.)

the answer is b i think

i really dont know but i will try okay.

so i think u would just add all them up and get your answer..