A house has walls made out of steel with the following properties: Thickness Density Thermal Conductivity Specific Heat mm 300 kg/m3 7800 w/m-K 50 J/kg-K 500 Сарacity Embodied MJ/kg 26 Energy Cost $/kg 0.70 The time that it will take, in hours, for the interior temperature to start changing after the exterior is exposed to a sudden temperature is:

1.25 A common procedure for measuring the velocity of an airstream involves the insertion of an electrically heated wire (called a hot-wire anemometer) into the airflow, with the axis of the wire oriented perpendicular to the flow direction. The electrical energy dissipated in the wire is assumed to be transferred to the air by forced convection. Hence, for a prescribed electrical power, the temperature of the wire depends on the convection coef- ficient, which, in turn, depends on the velocity of the air. Consider a wire of length L = 20 mm and diameter D = 0.5 mm, for which a calibration of the form V = 6.25 × 10-5 h² has been determined. The velocity V and the convection coefficient h have units of m/s and W/m².K, respectively. In an application involving air at a temperature of T = 25°C, the surface temperature of the anemometer is maintained at T₁ 75°C with a volt- age drop of 5 V and an electric current of 0.1 A. What is the velocity of the air? =

c)q1=87.7w   q2=4.62w i need answer for the last question

Insulating material is used to reduce heat loss from the heating furnace walls to the room. The surface temperature of the insulating material is 100 ° C and the other surfaces 20 ° C. Allowable heat loss up to 140 W / m2 from the wall. If the thermal conductivity of the insulation material is 0.05 W / (m ° C), calculate the required thickness of insulation. insulation thickness = Answer cm

Heat transfer by conductivity: One side of a 3 cm thick copper plate is held at 400°C and the other at 100°C. How much head transferred through the plate?

A house, for cooling purposes, consists of two zones: the atric area zone A and the living area zone B (see below figure). The living area is cooled by a 2 -ton air conditioning unit that removes 23,000 Btu/hr. The heat capacity of zone B is 1/6 °F per thousand Btu. The time constant for heat transfer between zone A and the outside is 3ℎr, between zone B and the outside is 6ℎr, and between the two zones is 6ℎr. If the outside temperature stays at 90°F, how warm does it eventually get in the attic zone A ?

List the forms of energy that contribute to the internal energy of a system