Molecular Physics | Thermodynamics Answers

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. 

Jill added 215J of heat energy to 14.5 kg of copper and 1.50 kg of water which are in

thermal contact with each other, both initially at 32.0^oC. What will be their final temperature?

(C_copper 0.385 J/g^oC, C_water 4.186 J/g^oC).

At the triple point of water the pressure of a fixed mass of gas is 2680 Pa. The temperature is changed to T while the volume of the gas is kept constant. The pressure is then 4870 Pa. i. Find the value of T. ii. What is the advantage of making this determination at such a low pressure?

A platinum resistance thermometer is calibrated in ice and steam. It is then used to find the temperature of an oil bath. The values of its resistance are: At the ice point: 25.6 Ω At the steam point: 35.6 Ω At

A fixed mass of gas at constant pressure has a volume of 200 cm3 at the ice point, 273.2 cm3 at the steam point and 525.1 cm3 at the melting point of a solid. What is the melting point of the solid on the constant pressure gas scale of temperature?

The resistance of a resistance thermometer at the ice point is 40 Ω. Its resistance at temperatures T1 and T2 are 48 Ω and 53.2 Ω respectively. What is the ratio of T2 and T1? 

A hot liquid at 80oC is added to 600 g of the same liquid originally at 10oC. When the mixture reaches 30oC, the total mass of liquid is?

A mercury-in-glass thermometer is to be used to measure the temperature of some oil. The oil has a mass of 32.0 g and a specific heat capacity of 1.40 J g–1K–1. The actual temperature of the oil is 54.0 °C. The bulb of the thermometer has a mass of 12.0 g and an average specific heat capacity of 0.180 J g–1K–1. Before immersing the bulb in the oil, the thermometer reads 19.0 °C. The thermometer bulb is placed in the oil and the steady reading on the thermometer is taken. Determine i. The steady temperature recorded on the thermometer ii. The ratio of change in temperature of the oil to the initial temperature of the oil. iii. Suggest, with an explanation, a type of thermometer that would be likely to give a smaller value for the ratio calculated.

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A machinist wishes to insert a brass rod with a diameter of 3 mm into a hole with a diameter of 2.996 mm. By how much would the machinist have to lower the temperature (in °C) of the rod to make it fit the hole?

A metal rod has a length of 100cm at 200°C. At what temperature will its lenght be 99.4cm. If the linear expansivity of the material of the rod is 150.0002/K