The thermal conductivity of wood is 1 BTU per hour, per square foot, for a temperature gradient of 1 F° per inch. Convert this to units of W/mK, knowing 1 F° = 5/9 C° 1 inch = 0.0254 m 1 foot = 0.3048 m 1 lb = 0.453593 kg 1 kcal = 4184 J I know there are conversions between BTU and joules/calories, but he says looking this up will cost us half of the question. So far all I've concluded (I think) is that the unit we need to convert is BTU·inch / hr·ft²·F° But I'm not sure how to get rid of the BTU without knowing a conversion factor... If I can get rid of the BTU I'm sure I'll be able to figure the rest out. Is there a way to do it without knowing anything else, maybe by using the definition of a BTU? I'm also confused about the difference between a degree Fahrenheit (°F) and a Fahrenheit degree (F°).