Athin electrical heating element provides a uniform heat flux qo" to the outer surface of a duct through which air flows. the duct wall has a thickness of 10 mm and a thermal conductivity of 20 w/m·k. (a) at a particular location, the air temperature is 30°c and the convection heat transfer coefficient between the air and inner surface of the duct is 100 w/m2·k. what heat flux is required to maintain the inner surface of the duct at ti = 58°c? (b) for the conditions of part (a), what is the temperature to of the duct surface next to the heater?

We want to calculate the total metabolic heat generated by a singing canary taking into account heat transfer by radiation, convection and exhaling air. the air temperature is 20 oc, canary’s body internal and surface temperature is 33oc, external body surface convective heat transfer coefficient is 25.2 w/m2 .k, temperature difference between the inhaled and exhaled air is 4.3 oc, the ventilation rate is 0.74 cc of air per second, specific heat of air is 1.0066 kj/kg.k and density of air is 1.16 kg/m3 . assume the canary’s body to be a cylinder with 7 cm diameter and 9 cm length, and heat exchange is from the side as well as the top and bottom of cylinder. calculate 1) the net rate of heat lost by radiation, assuming heat gained by the bird through radiation from the surroundings is 11.5 w; 2) rate of heat transferred by convection to the surrounding air; 3) rate of heat transferred in the exhaling air without considering any internal evaporation; 4) total metabolic power.

Which of these is not a possible type of energy transformation? a. electrical energy into light energy b. sound energy into nuclear energy c. potential energy into kinetic energy d. kinetic energy into mechanical energy

By what factor does the drag force on a car increase as it goes from 65 to 110 km/h?