3. What is the kinetic energy of an electron, in joules, that has a mass of 9.109 x 10-28 g and moves at a speed of 2.2 x 103 km/s?
Convert the mass of the electron from g to kg.
9.109 x 10-28 g = 9.109 x 10-31 kg
The speed of the electron is converted from km/s to m/s
2.2 x 103 km/s = 2.2 x 106 m/s
Now we can calculate the kinetic energy.
\(\displaystyle \frac{1}{2}\times\;(9.109\times\;10^{-31}\;kg)\times\;(2.2\times\;10^6\;m/s)^2\;=\;2.2\times\;10^{-18}\frac{kg⋅m^2}{s^2}\)
\(\displaystyle one\;\frac{kg⋅m^2}{s^2}\;=\;1\;J\)
The amount of kinetic energy for this electron is 2.2 x 10-18 J.
Thank you. The answer has been fixed. The problem was set up correctly but the v was not squared when entered into the calculator.