Question

A 0.00260 kg air‑inflated balloon is given an excess negative charge q 1 = − 3.25 × 10 − 8 C by rubbing it with a blanket. It is found that a charged rod can be held above the balloon at a distance of d = 0.0520 m to make the balloon float. In order for this to occur, what polarity of charge must the rod possess? proton ,positive, neutral, negative?

How much charge q 2 does the rod have? Model the balloon and rod as point charges. The Coulomb force constant is 1 / ( 4 π ϵ 0 ) = 8.99 × 10 9 N·m2/C2, and the acceleration due to gravity is g = 9.81 m/s2.

Answer 1

the balloon must be repulsed by the tod.. therefore it must have same type of charge of the balloon.