00:01
So for this question, we have to realize that, shift everything down a bit, we have to realize that we have this equation, delta l is equal to alpha, l0, delta t.
00:18
And so the change in length is equal to alpha, which is our coefficient of a linear expansion, times by our reference length, times by the change in temperature and this length can therefore just be the same as our diameter.
00:34
So the change of diameter is equal to alpha times by d0 delta t.
00:40
So simply for part a it asks find the penny's diameter on a hot day in death value with the temperature of 48 kelvin.
00:46
Well let's start off with delta temperature is equal to 48 minus 20.
00:56
48 .0, that again, 48 .0 degrees minus 20 .0 degrees, which is equal to 28 degrees kelvin.
01:13
And therefore, delta d is equal to our alpha, which is 2 .6 times 10 to the minus 5, multiplied by d0, which is 1 .9000, multiplied by 28 .0 kelvin, which is equal to, let's put this into our calculator, times 10 to minus 5, times 1 .9 times 28.
01:39
That gives us 1 .38 times 10 to the minus 3 centimeters...