Near the surface of earth an electric field points radially downward and has a magnitude of approximately 100 n/c. what charge (magnitude and sign) would have to be placed on a penny that has a mass of 3g to cause it to rise into the air with an upqard acceleration of 0.19 m/s^2

C

Sign-Negative

Explanation:

We are given that

Electric field = (Radially downward)

Acceleration=(Upward)

Mass of charge=3 g=kg

1kg=1000g

We have to find the magnitude and sign of  charge would have to be placed on a penny .

By newton's second law

Substitute the values then we get

Substitute the values then we get

C

Sign of charge =Negative

Because electric force acting  in opposite direction of electric field therefore,charge on penny will be negative.