- #1
Tadhgrrr
- 4
- 2
Hello everyone!
First time asking a question here, go easy on me!
I am a first year Mech-Eng student in Ireland, and I need some guidance from one of the amazing brains here at physicsforums.
I am told by my thermofluids lecturer that in thermal expansion, the amount of material expanding is "irrelevant", and will expand the same amount. Allow me to explain this better;
She says that if you take a 100mm diameter solid steel cylinder, and a steel pipe with an external diameter of 100mm, but with a gauge thickness of, say 5mm, then if both are heated the same, the amount each specimen will expand linearly will be the same...i.e the final external diameter will be the same.I really hope I am just being thick, because my lecturer should know this stuff, but it doesn't make sense to me. I feel that if a solid cylinder of steel is heated, it can only expand outwards, increasing outwards linearly and cubically. If the same heat is applied to a hollow pipe of the same material, I feel the hollow center would allow for some inward expansion, making the final values for diametric expansion different... I also imagine the more material there is, the greater the total expansion will be...i.e; if there are 5 iron atoms side by side and they expand uniformly, won't that be a smaller amount of linear expansion than if there were 5,000,000 atoms side by side?
I hope I explained that well enough. This lecturer is great, and if this sounds totally nuts, she most likely misunderstood my goofy, confusing questions!
who is right? And could a resident genius please elaborate?
Thanks very much
T
First time asking a question here, go easy on me!
I am a first year Mech-Eng student in Ireland, and I need some guidance from one of the amazing brains here at physicsforums.
I am told by my thermofluids lecturer that in thermal expansion, the amount of material expanding is "irrelevant", and will expand the same amount. Allow me to explain this better;
She says that if you take a 100mm diameter solid steel cylinder, and a steel pipe with an external diameter of 100mm, but with a gauge thickness of, say 5mm, then if both are heated the same, the amount each specimen will expand linearly will be the same...i.e the final external diameter will be the same.I really hope I am just being thick, because my lecturer should know this stuff, but it doesn't make sense to me. I feel that if a solid cylinder of steel is heated, it can only expand outwards, increasing outwards linearly and cubically. If the same heat is applied to a hollow pipe of the same material, I feel the hollow center would allow for some inward expansion, making the final values for diametric expansion different... I also imagine the more material there is, the greater the total expansion will be...i.e; if there are 5 iron atoms side by side and they expand uniformly, won't that be a smaller amount of linear expansion than if there were 5,000,000 atoms side by side?
I hope I explained that well enough. This lecturer is great, and if this sounds totally nuts, she most likely misunderstood my goofy, confusing questions!
who is right? And could a resident genius please elaborate?
Thanks very much
T