Near the surface of Earth, an electric field points radially downward and has a magnitude of approximately 100 N/C. 1) What charge (magnitude and sign) would have to be placed on a penny that has a mass of 3.11 g to cause it to rise into the air with an upward acceleration of 0.190 m/s2

Negative charge with a magnitude of 5.9*10^-6C

Explanation:

In order to calculate the required charge, for the penny is able to rise into the air with the given acceleration, you take into account the following formula for the electric force and also the Newton second law:

           (1)

FE: electric force:

q: charge = ?

E: electric field = 100N/C

m: mass of the penny = 3.11g = 3.11*10^-3kg

a: acceleration of the charge = 0.190m/s^2

The positive charges experiences a force in the same direction of the electric field, and the negative charge, a force in a opposite direction.

The electric field points downward, then, the charge is negative (it is acceleration upwards).

Next, you solve the equation (1) for a, and replace the values of the other parameters:

The magnitude of the charge is 5.9*10^-6C and its sign is negative