A 60-μC Charge Is Held Fixed at the Origin and a −20-μC

Multiple Choice

A 60-μC charge is held fixed at the origin and a −20-μC charge is held fixed on the x axis at a point x = 1.0 m. If a 10-μC charge is released from rest at a point x = 40 cm, what is its kinetic energy the instant it passes the point x = 70 cm?

A) 9.8 J
B) 7.8 J
C) 8.8 J
D) 6.9 J
E) 2.8 J