It is due to the excess stress.
The total mechanical energy of the notebook is <u><em>19J</em></u>.
Mechanical energy is the sum of potential energy and kinetic energy. It has no kinetic energy, because it's not moving. So its potential energy is all the mechanical energy it has.
Variables:
Source charge, Q = 3 micro C = 3 * 10^ - 6 C
E = electric field = 2.86 * 10 ^5 N/C
K = 8.99 * 10^9 N * m^2 / C
d = distance = ?
Formula:
E = K * Q / (d^2) => d^2 = K * Q / E
=> d^2 = 8.99 * 10^9 N * m^2 / C * 3 * 10^ -6 C / (2.86 * 10^ 5 N/C)
d^2 = 9.43 * 10 ^ -2 m^2
=> d = 3.07 * 10^-1 m
Answer: 0.307 m
Note: it is a long distance due to the Electric field is very low