Answer: Q=42.45W
Explanation:
Q=πA × ∆t/∆X, where;
Q= Rate of heat
π=coefficient of thermal conductivity
A= Area
∆t= change in temperature
∆x= change in thickness
Q= 0.023 × 1.7 × 33-(-5)/0.035
Q= 0.0391×38/0.035
Q = 1.4858/0.035
Q= 42.45w
Answer:
Low-temperature blackbody
Explanation:
There are 3 types of blackbody temperatures.
Low-temperature blackbody
High temperature extended area blackbody
High-temperature cavity blackbody
A Low-temperature blackbody is a type of black body radiation that has the range of -40° C to 175° C, typically between 233 K and 448 K. A perfect fit for the temperature range mentioned in the question, "a few hundred Kelvin". Therefore, it's the kind of blackbody temperature that the object would emit.
When the concrete structure avails it maximum strength, it is safer to place construction load on it. Usually, the concrete gain it maximum strength after 28 days. Concrete when cast take initial settlement on 7 days. Curing is done continuously through the period so that there is no crack occur due to heat transfer. There are various method of concrete curing. On a horizontal surface/ roof/ floor, curing is done through ponding or spreading wet sheets. Testiment/ sample of the concrete are cured by immersion in water tank. After 28 days of curing, concrete gains it maximum strength and can be used for test or usage. Construction load limit is considered in designing/ proportioning the specimen. So the applied load is equal or less than the limit for which it is actually designed.