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soomoon		#1 Posted : 23 February 2023 03:38:49(UTC)
Rank: Advanced Member Groups: Registered Joined: 22/02/2023(UTC) Posts: 34 Location: Seoul Was thanked: 1 time(s) in 1 post(s)		α= 0.0001 Δt = 50 ℃ L=40m Δl = α*Δt*L= 0.02m but result is Δl = 0.1293 K m The unit of Δt applied K instead of ℃. Δt = 323.15 K How can i get the result 0.02m
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overlord		#2 Posted : 23 February 2023 03:51:43(UTC)
Rank: Advanced Member Groups: Registered Joined: 23/07/2013(UTC) Posts: 1,131 Was thanked: 512 time(s) in 341 post(s)		There is delta temperatures for that. For unit conversion, 0°C = 273.15K. 50°C = 323.15K. Unitwise 1*Δ°C = 1*K obviously. In your calculation, ΔT become 323.15K. But it should be 50K actually. This is because °C is converted to K. Use delta versions for temperature changes. Regards
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soomoon		#3 Posted : 23 February 2023 04:07:01(UTC)
Rank: Advanced Member Groups: Registered Joined: 22/02/2023(UTC) Posts: 34 Location: Seoul Was thanked: 1 time(s) in 1 post(s)		thank you. can the unit of Δl be expressed in just (mm)?
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overlord		#4 Posted : 23 February 2023 04:11:10(UTC)
Rank: Advanced Member Groups: Registered Joined: 23/07/2013(UTC) Posts: 1,131 Was thanked: 512 time(s) in 341 post(s)		You have to have a K divisor for that. If you put a K as denominator for α, that will do. Or you can put as divisor for the equation. But alpha makes more sense. Regards
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Kenny Lemens		#5 Posted : 23 February 2023 17:12:45(UTC)
Rank: Advanced Member Groups: Registered Joined: 11/01/2018(UTC) Posts: 134 Location: Wisconsin Was thanked: 62 time(s) in 39 post(s)		Greetings! The Coefficient of Expansion is not unitless, it has units ｢1 / change in temperature｣; I would apply the unit directly to α. Just for reference, here is my definition of α for aluminum: Hope this helps! -Kenny Lemens, P.E. ᵂᴵ
		"No matter where you go, there you are." -Buckaroo Banzai Hotkeys: https://en.smath.com/for...rce.ashx?a=45771&b=2
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mkraska		#6 Posted : 23 February 2023 21:12:49(UTC)
Rank: Advanced Member Groups: Registered Joined: 15/04/2012(UTC) Posts: 1,990 Was thanked: 1128 time(s) in 724 post(s)		German Al behaves significantly different (23 µm/(m*K) which is approx 13 µm/(m*°F)), your value looks more like that for german steel (12 µm/(m*K)).
		Martin Kraska Pre-configured portable distribution of SMath Studio: https://smath.com/wiki/SMath_with_Plugins.ashx
1 user thanked mkraska for this useful post.		on 23/02/2023(UTC)
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Kenny Lemens		#7 Posted : 23 February 2023 23:50:34(UTC)
Rank: Advanced Member Groups: Registered Joined: 11/01/2018(UTC) Posts: 134 Location: Wisconsin Was thanked: 62 time(s) in 39 post(s)		Thanks mkraska1 Thank you for identifying my error, I had my values for Aluminum and Steel flipped. - Kenny Lemens, P.E. ᵂᴵ
		"No matter where you go, there you are." -Buckaroo Banzai Hotkeys: https://en.smath.com/for...rce.ashx?a=45771&b=2
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