Answer:
So it would need a charge of 0.115C for a upward force to act and cancel the force of gravity.
Step-by-step explanation:
Fb = Fg
so
qvb= mg ⇒ q = mg/vB = 0.2 *10∧-3 * 9.8/853.44 * 20 * 10∧-6
= 0.115C
note:2800ft/sec = 853.44m/s
So it would need a charge of 0.115C for a upward force to act and cancel the force of gravity.