Physics
(i) How is the transference of heat energy by radiation prevented in a calorimeter?
(ii) You have a choice of three metals A, B and C, of specific heat capacities 900 Jkg-1°C-1, 380 Jkg-1°C-1 and 460 Jkg-1°C-1 respectively, to make a calorimeter. Which material will you select? Justify your answer.
Answer
(i) To prevent heat transference by radiation, the outer and inner surfaces of calorimeter are polished.
(ii) For calorimeter, metal B will be used.
The reason is, it's specific heat capacity is lowest, so it will take least heat from its contents to acquire the temperature of contents.
Related Questions
(i) A boy uses a single fixed pulley to lift a load of 50 kgf to some height. Another boy uses a single movable pulley to lift the same load to the same height. Compare the effort applied by them. Give a reason to support your answer.
(ii) How does uniform circular motion differs from uniform linear motion?
(iii) Name the process used for producing electricity using nuclear energy.
A pulley system with V.R. = 4 is used to lift a load of 175 kgf through a vertical height of 15 m. The effort required is 50 kgf in the downward direction. (g = 10 N kg-1)
Calculate:
(i) Distance moved by the effort.
(ii) Work done by the effort.
(iii) M.A. of the pulley system.
(iv) Efficiency of the pulley system.
Calculate the mass of ice needed to cool 150 g of water contained in a calorimeter of mass 50 g at 32°C such that the final temperature is 5°C.
Specific heat capacity of calorimeter = 0.4 J g-1 °C-1
Specific heat capacity of water = 4.2 Jg-1°C-1
Latent heat capacity of ice = 330 Jg-1
(i) Name the radiations which are absorbed by greenhouse gases in the earth’s atmosphere.
(ii) A radiation X is focused by a particular device on the bulb of a thermometer and mercury in the thermometer shows a rapid increase. Name the radiation X.
(iii) Name two factors on which the heat energy liberated by a body depends.