Answer:
1.6 pF
Explanation:
The capacitance of a parallel-plate capacitor in air is given by:
where
is the vacuum permittivity
A is the area of each plate
d is the separation between the plates
In this problem we have:
- Separation between the plates: d = 5.00 mm = 0.005 m
- Area of the plates: 
Therefore, the capacitance is
A girl standing on a floor would have two opposite forces acting on it. These forces are the weight and the normal force. Since no other forces are acting and that the girl is at rest, then the weight must equate to the normal force. Therefore, the supporting force would be:
F = mg = 55kg (9.81 m/s^2) = 539.55 N
The third choice is correct
Answer: a) 8.2 * 10^-8 N or 82 nN and b) is repulsive
Explanation: To solve this problem we have to use the Coulomb force for two point charged, it is given by:
Replacing the dat we obtain F=82 nN.
The force is repulsive because the points charged have the same sign.
