00:01
In this question, we're considering her an electron, and of course the electron has a mass of 9 .1 times 10 to the minus 31 kilograms.
00:07
It tells us the kinetic energy of the electron is 20 electron volts, and it wants us to find the electron speed in units of meters per second.
00:14
It also tells us that the well, the potential well, is 0 .15 nanometers wide, but we're not going to actually need to use that to calculate the speed.
00:22
But what we do need to do is convert electron volts into joules, because if we want meters per second, this is si units, and electron volts is not in s i units.
00:32
So we need to get it into units of joules so we can more easily calculate the speed in meters per second.
00:38
So i do that by converting it, multiplying it by 1 .6 times 10 and minus 19 joules per electron volt to get my kinetic energy in units of joules.
00:46
Now we can just use the classical equation for kinetic energy, which says that kinetic energy is equal to 1 half mv squared, where m here is just the mass of the electron...