A woman's marathon runner set a world record by running 18.08 km in 1 hr. Her mass was 55 kg. If she ran with a constant velocity, what was her kinetic energy?

two charges are fixed in place on the x-axis as shown. the charge at x = 0 is negative and has magnitude q = 2 μcoulombs (1 μcoulomb = 10-6 coulombs). the charge at x = d, (d = +12 cm), is positive and has magnitude q = 4 μcoulombs. find a point x = xo along the x-axis at which the electric field is zero.