Preparing multiple refreshing drinks for your friends, you used several cubic ice cubes (3 cm per side). The ice cubes are initially at a uniform temperature of -18 C and have a thermal conductivity and diffusivity of 2.22 Wm-K- and 0.124 x 10-7 m²s-, respectively. One of the ice cube fell on a thick kitchen towel that was laid on the counter top. Consequently, the top and lateral surfaces of the ice cube are exposed to a constant and uniform combined convection (h 17 W m-2K-1), while the heat transfer on its bottom surface is minimized due to the presence of the thick towel (assume ġlbottom = 0). The temperature of the air and surroundings in the kitchen is constant at 20 'C. a. How long will it take for the ice cube to start melting? b. What will be the minimum temperature of the ice cube at that time (see a.)?

As shown in the figure, a tank fitted with an electrical resistor of negligible mass holds 2 kg of nitrogen (N₂), initially at 27°C, 0.1 MPa. Over a period of 10 minutes, electric power Eelectric of 0.35 kW is provided to the resistor. During this same period, a heat transfer of magnitude 10.5 kJ occurs from the nitrogen to its surroundings. Assume ideal gas behavior, but do not assume constant specific heats. Determine the final temperature, in °C, and the final pressure, in MPa. Nitrogen, N₂ m = 2 kg T₁ = 27°C P₁ = 0.1 MPa eeeeeee Qout, 12 = 10.5 kJ É electric At 10 minutes

thermodynamics

Determine the specific heat capacities at constant volume and constant pressure for nitrogen, given that its molecular weight is 28 and the adiabatic index for expansion and compression is 1.4. The universal gas constant is 8314 Jmol-1K-1.  Explain the difference in the values for the two specific heat capacities.