00:01
In this problem, we're going to talk about relativistic energy.
00:03
Remember that the rest energy of a particle is mc squared, while the total energy is mc squared gamma.
00:14
And what we need to notice is that the power emitted by the sun, in the form of energy, is 3 .8 times 10 to the 26 watts.
00:27
And also the mass of the sun is equal to 2 .2 .2 .2 .2 .2 .2 .2.
00:29
And also the mass of the sun is equal to 2 .2.
00:34
Times 10 to the 30 kilograms.
00:39
In question a, our goal is to calculate how much mass is lost by the sun each year.
00:48
Well, first, let's calculate the energy that is produced by the sun each year, and then we can convert it to mass by using the energy mass equivalents.
01:00
So energy is power times the time.
01:03
The power is 3 .8 times 10 to the 26 watts.
01:10
You have to multiply it by 3 ,600 seconds an hour times 44 hours a day times 365 days a year...