A small bead of mass 2.0g carrying an unknown charge q is released from rest 1.20m from a fixed charge q1=+5.0μC. When the bead reaches 0.40m from q1, its speed is 30ms−1. Assuming no non-conservative forces act, what is the charge q on the bead?
a) +12μC
b) −24μC
c) −12μC
d) +25μC