28/03/2020Thermal Properties and Processes – Expansivity, Heat Transfer(Senior Class Physics Study by Topics) 0Comments by Gate Academy Welcome to your Thermal Properties and Processes - Expansivity, Heat Transfer(Senior Class Physics Study by Topics) NAME EMAIL PHONE NUMBER 1. The outer ends of two bars A and B are at 100°C and 50° respectively. Calculate the temperature at the welded joint if they have the same cross-section and the same length and their thermal conductivities are in the ratio of A:B = 7:5.80.548°C20.157°C79.166°C58.147°C2. A pure substance would freeze or solidify at itscondensation pointmelting pointsublimation pointboiling point3. The temperature of a body can be negative on the Kelvin scale.TrueFalse4. 540g of ice at 0°C is mixed with 540g of water at 80°C. What is the final temperature of the mixture?40°CLess than 0°80°C0°C5. Temperature is a microscopic concept.FalseTrue6. A milkman boils the milk before distributing it in the pots. He raises the temperature of the milk from 10 °C to 130 °C with the thermal energy of 120000 J. If the mass of the milk is 25 kg, the specific heat capacity of the milk would be40 J kg -1 °C-1120 J kg -1 °C-1160 J kg -1 °C-180 J kg -1 °C-17. The heat capacity of a material defined as ___________C = dT/dQC = 1/m . dE/dTC = m . dE/dTC = dQ/dT8. When potassium is added to water, it is seen that the lower region becomes warm first and becomes less dense. It then moves up and the more dense cold water comes down and the process goes on. What is the process taking place?ConvectionRadiationConductionPurification9. Why is the roof of buildings painted whiteBecause it reflects radiationsBecause it is cheaperBecause it absorbs radiationBecause it conducts heat10. The energy due to which the molecules held at a fixed position vibrate, this energy is termed asphysical energyexternal energychemical energyinternal energy11. Solids with weekly bonded electrons are good conductors of heat.FalseTrue12. Why locations next to large water bodies tend to have a moderate climate than those further inland?Because of the water in cloudsBecause of the heating effects of sunBecause of the latitudeBecause of specific heat of water13. What effect does the addition of thermal energy have on a material?Thermal expansionThermal contractionReproductionNo change14. How is the spalling resistance index defined?αlΔThS/αEk/cpPP/A15. A green glass heated in a furnace when taken out in dark glows red.TrueFalse16. A block of copper weighs 3.0 kg. Copper has a specific heat capacity of 390 J kg-1K-1. It is cooled in the freezer so that the temperature drops from 25.0oC to 0.0oC. What is the total energy lost by the block of copper?32950 J29250 J22950 J23400 J17. What happens when a material is heated?It contractsIt meltsIt expandsIt bursts18. What is the SI unit of specific heat capacity?Jkg/KJ/(kgK)JK/kgJ/kg19. Mercury has the boiling point of357 °C257 °C157 °C57 °C20. In an experiment, 100 g of liquid requires 12600 J of thermal energy to raise it from 30 °C to 60 °C, the thermal capacity of 100 g of water is300 J K420 J K-1420 J K300 J K-121. Which of the following is an effective coolant?AcidsMecuryOilWater22. The internal energy comprises of two types of energies, those arekinetic and magnetic energykinetic and potential energymechanical and electrical energymagnetic and electrical energy23. What happens when you heat china having some dark paintings engraved on it at 1000°C and then examine it in a dark room immediately?The whole china dish will be brightThe dark painting will appear much brighterThe china dish doesn’t glowThe china dish will develop patterns24. Calorie is defined as the amount of heat required to raise the temperature of 1g of water by 1°C and it is defined under which of the following conditions?From 3.5°C to 4.5°C at 76mm of HgFrom 98.5°C to 99.5°C at 760mm of HgFrom 14.5°C to 15.5°C at 760mm of HgFrom 13.5°C to 14.5°C at 76mm of Hg25. When one end of the rod is heated, the molecules at the hot end vibrate with higher amplitude and transmit the heat from one particle to the adjacent particle and so on. What is the process?ConvectionRadiationTransmittanceConduction26 out of 25Time is Up!