Which must exist for electric charges to flow?

force is mass*acceleration.

we have a very small mass: 11.4*0.001 kg

if we want 0.035n of force, we need an acceleration:

0.035 = 11.4*0.001*a

a = 0.035/(11.4*0.001) m/s^2

when heated, the valance electrons increased their speed and transferred the heat from electron to electron.   i just took the test.

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.