What must the charge (sign and magnitude) of a particle of mass 1.40 gg be for it to remain stationary when placed in a downward-directed electric field of magnitude 640 N/CN/C

the charge of the particle is -2.144 x 10⁻⁵ C.

Explanation:

The force acting on the particle is calculated as;

F = EQ = mg

where;

Q is magnitude of the charge of the particle

since the magnetic field is acting downward, the force must be acting upward in opposite direction.

Thus, the charge of the particle will be -2.144 x 10⁻⁵ C.

he kicked it 10 feet straight up into the air? i think this works.