Question

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?

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.