Unit of thermal conductivity in S.I. units is (a) J/m2 sec    (b) J/m °K sec (c) W/m °K    (d) (a) and (c) above (e) (b) and (c) above.

A hot small copper ball [c in kJ/kg.°C, k in W/m.°C] is suddenly placed in water maintained at 100 °C. The convection heat transfer coefficient is h in W/m². ºC. Derive equation to calculate the time required to reduce ball to temperature T.

The mass (m)of a substance is equal to (Take M-molar mass & N- number of moles) M/N O M+N MN O M-N Which of the following relation is correct? du=Tds – pdv dh=Tds - pdv du=Tds + vdp dh=Tds / vdp

A skater is rotating about a single point on the ice as shown below. She changes her position from the one shown on the left to the one shown on the right. For each of the following quantities, state if the quantity stays the same, increases, or decreases. Be sure to give a reason for each answer. dreamstime.m com (a) Moment of Intertia (b) Total Linear Momentum (c) Angular Momentum (d) Kinetic Energy (e) Angular Velocity

Unit systema) Determine the units of pressure in the equation pv=RT v: specific volume, m3/kg R: constant in kJ/kgK, T: temperature in K

The density of air at room temperature is about 1.2 grams/cm³. Estimate the mass of air inside an average automobile. Select one: O a. 20 kg O b. 2 grams O c. 2000 kg O d. 2 kg O e. 200 kg

When a 2.30-kg object is hung vertically on a certain light spring described by Hooke's law, the spring stretches 3.13 cm. (a) What is the force constant of the spring? N/m(b) If the 2.30-kg object is removed, how far will the spring stretch if a 1.15-kg block is hung on it? cm(c) How much work must an external agent do to stretch the same spring 8.60 cm from its unstretched position? J

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 ?

Conduction Heat Transfer X material (a) material (b) . both (a) and (b) have the same thermal conductivity the temperature distribution is independent of thermal conductivity it's not that simple 9. Fin efficiency is defined as: • tanh (mL) (hP/k Ac)1/2 (heat transfer with fin) / (heat transfer without fin) (actual heat transfer through fin) / (heat transfer assuming all fin is at T = Tb) (Tx=L-Tf)/(Tb-Tf) 10. For an infinite fin, the temperature distribution is given by: (T-Tf)/(Tb-Tf)= e-mx. The heat flow through the fin is therefore given by: k (Tb-Tf)/L ● zero, because the fin is infinite ● infinite because the fin is infinite ● (Tb-Tf) (hP/k Ac)1/2 ● (Tb – Tf) (h P / k Ac)1/2 tanh (mL) 11. The Biot number, Bi, is defined as: • Bi=hk/L • Bi=hL/k • Bi= k/LH • Bi=qL/k • Bi=p UL/k 12. For a plate of length L, thickness, t, and width, W, subjected to convection on the two faces of area L x W. What is the correct length scale for use in the Biot number? . L ● W ● t • t/2 • L/2 13. If Bi…

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