Due to electric effects on the earth and in the atmosphere, there is an electric field near the earth's surface that points down. Assuming the electric field is uniform with a magnitude of 150 N/C, what charge would a 145g baseball need to float as though it were weightless?

Question

I am quite confused by what formula I need to apply to this, and what condition it needs to meet. The ball needs to acquire enough charge to overcome a 150 N/C electric field....but how to represent that numerically as one side of an equation?

Answer 1

force gravity=electric force
9.8N/kg*massball=Eq
q= 9.8*massball/E=
massball=.145kg
so q= ...

Answer 2

Electric charge is distributed uniformly along an infinitely long, thin wire as shown in figure below. The linear charge density λ is 1.5 cross times 10 to the power of negative 10 end exponent space C divided by m.

q14.png

Find the magnitude of electric field at 108 cm from the infinitely long wire.