Why is it important for the thermometer to be fully immersed in the water but does not touch the bottom of the inner vessel in doing the experiment for latent heat of fusion of ice? * The thermometer will be damaged if it will touch the inner vessel of the calorimeter. The thermometer in contact with the bottom of the vessel will cause the final temperature to be too warm and gives an experimental value of the latent heat of fusion that is too low To have an equilibrium temperature of too high or too low.

4. *You accidentally release a helium-filled balloon that rises in the atmos- phere. As it rises, the temperature of the helium inside decreases from 20 °C to 10 °C. What happens to the average speed of helium atoms in the balloon and the thermal energy of the helium inside the balloon? Describe the assumptions you made.

*The primary and secondary mirrors of a space telescope are assembled using zerodur spacers in an engineering laboratory in which the room temperature is 20 °C. In space the telescope will drop to -30 °C. If the distance between the mirrors is exactly 80 cm in the lab, how much would the length of the zerodur spacer change in space? The properties of the material Zerodur can be found in the following table. Properties of Zerodur Coefficient of Thermal Specific Heat Expansion 2 x 10-8 [K-¹] 3347.20 [J/kg/K] Zerodur 50⁰ 50⁰ 80 cm

4) A ground source heat pump heats a building by extracting heat from the ground and pumping it into the building. Define: Qc = heat extracted from the ground, Qn= heat pumped into the building, W = electric energy used by the heat pump, Tc= temperature of the ground, T = temperature of building (Qc, Qn, and W are positive by definition). Assume Tr > Tc. a) Draw a diagram showing energy flow in and out of the heat pump. b) Write a general expression for the change AS in the entropy of the "universe", that is the heat pump plus the cold and hot reservoirs, in terms of the quantities defined above. Now assume ideal (reversible) operation, and take Te= 10 °C and Tp= 20 °C. What is the coefficient of performance (ČOP) of the heat pump? By what factor would this change if we had Tc = 0 °C instead?