00:01
What is the stress in the cement on a day of temperature 50 .0 .0 celsius if the cement was poured with no space at temperature 20 .0 degrees celsius.
00:12
Well, first off, let's just find delta t, which is, of course, just subtracting ti from tf.
00:22
I mean, this is a pretty simple calculation, but i'll just say, well, yep, this is going to be 30 degrees celsius.
00:29
And we also want to go look in our book and find the linear expansion coefficient alpha for cement, which is of course equal to 12 times 10 to negative 6 degrees celsius than negative 1.
00:45
Now to find stress, we can use the equation e, which is the young's modulus, is equal to stress over strain, which is of course equal to stress, which is, you know, what we will.
01:03
Want to find over strain which is delta l over l initial okay well we have we remember the equation for linear expansion delta l is equal to l initial alpha delta t can also just rearrange this so delta l over l initial is equal to alpha delta t and we can plug in and solve for delta l over l initial delta l over initial is equal to 12 times 10 to negative 6 times 30 is equal to 3 .6 times 10 to negative and so when we turn to this equation, which one? just keep it in the screen...