Molecular Physics | Thermodynamics Answers

On a still -10°C day, an air film coats the inside of a single glazed glass (k= 0.84 Wm^-1 K ^-1) window. The window is 75 cm by 1m has 3mm thick glass . Assume h= 10. The inside temperature is 20°C . Find the rate of thermal energy flow .

A car plunges into a lake (water density 𝜌 = 1000 kg m^-3). Using the steps below, calculate the resultant hydrostatic force on the door, and the distance from the bottom of the door to the point at which the force acts. Discuss if someone could open the door and describe the what the effect would be of opening a window. Note that the door is hinged at 𝐶𝐷.

    i.     Using the standard table method, find the

a.      Position of the centroid (𝑥_𝑐, 𝑦_𝑐), its depth ℎ_𝑐 and

b.     second moment of area 𝐼_𝑐 about the horizontal axis through the centroid

of the door by splitting it into rectangles, triangles and quarter-circles.

ii.     Compute the hydrostatic force on the door using 𝐹 = 𝜌 𝑔 ℎ_𝑐 𝐴. iii.  Find the depth of the centre of pressure using ℎ_𝑃 = ℎ_𝑐 + _ℎ^𝐼𝑐^𝑐_𝐴. 

On a still -10°C day, an air film coats the inside of a single glazed glass (k= 0.84 Wm^-1 K ^-1) window. The window is 75 cm by 1m has 3mm thick glass . Assume h= 10. The inside temperature is 20°C . Find the rate of thermal energy flow .

How much water at (20°C) is required to cool a 5kg burning wood log from 300°C to 80°C ?