Do you mean 12 km/h because this is a measurement of distance
First:
5 cm = 0,05 m
Now, the formula:
F = k * (qq') / r²
Replacing:
F = 9x10⁹ * (55x10⁸ * 1x10⁷) / 0,05²
F = 9x10⁹ * (5,5x10¹⁶ / 2,5x10⁻³)
F = 9x10⁹ * 2,2x10¹⁹
F = 1,98x10²⁹
The force between the charges is 1,98x10²⁹ Newtons.
That particles of matter<span> are always in </span>motion<span> </span>
B. 8.89 (hope this helped.)
You can solve by just doing 3.5in * 2.54
It should be gown, mask, gloves, and then goggles!