A person scuffing her feet on a wool rug on a dry day accumulates a net charge of -93μC .How many excess electrons does she get?
By how much does her mass increase?
For physics problems, it’s best to start off by listing everything that’s given:
Net charge (Q) = -93 μC
Although not given, the following info should be known:
mass of electron (me) = 9.1 x 10^-31 kg
charge of electron (q) = -1.6 x 10^-19 C
For the first question:
The number of electrons (N) equals the total charge divided by the charge per electron:
N = Q/q = (-93)(10^-6) / (-1.6)(10^-19)
N = 5.8 x 10^14 electrons
If the she has 5.8 x 10^14 excess electrons, then her mass increases by the mass per electron times each of the excess electrons:
In other words:
Increase in the mass of lady
= 5.3 x 10^-16 kg
Hope I helped..
elementary charge = 1.60217657 × 10-13 μC
93μC / 1.60217657 × 10-13 μC/electron = 58.05 x 10^13 electrons
9.10938291×10−31 kg/electron * 58.05 x 10^13 electrons = 5.29 x 10^-16 kg