:A 10 kW drilling machine is used to drill a bore in a small aluminium block of mass 8.0 kg. How much is the rise in temperature of the block in 2.5 minutes, assuming 50% of power is used up in heating the machine itself or lost to the surroundings. Specific heat of aluminium =` 0.91 J g^-1 K^-1`.

A copper block of mass 2.5 kg is heated in a furnace to a temperature of 500^2C and then placed on a large ice block. What is the maximum amount of ice that can melt? (Specific heat of copper = 0.39 J g-^1K ^-1 , heat of fusion of water = 335 J g^-1)

A ‘thermacole’ icebox is a cheap and efficient method for storing small quantities of cooked food in summer in particular. A cubical icebox of side 30 cm has a thickness of 5.0 cm. if 4.0 kg of ice is put in the box, estimate the amount of-ice remaining after 6 h. The outside temperature is 45 ^@C , and co-efficient of thermal conductivity of thermacole is 0.01 J s^-1.m-^1 K-^1 . [Heat of fusion of water = 335 x 103 J kg^-1

In an experiment on the specific heat of a metal, a 0.20 kg block of the metal at 150^@C is dropped in a copper calorimeter (of water equivalent 0.025 kg) containing 1-50 cm^3 of water at 27^@C . The final temperature is 40^@C . Compute the specific heat of the metal. If heat losses to the surroundings are not negligible, is your answer greater or smaller than the actual value for specific heat of the metal?

A brass boiler has a base area of 0.15 m2 and thickness 1.0 cm. It boils water at the rate of 6.0 kg/min when placed on a gas stove. Estimate the temperature of the part of the flame in contact with the boiler. Thermal conductivity of brass = 109 J s ^-1m^- 1K^-1 , Heat of vaporisation of water = 2256 xx 10^3 J kg^-1 .

In Millikan’s oil drop experiment, what is the terminal speed of an uncharged drop of radius 2.0 xx 10^-5m and density 1.2 xx 10^3 kg m^-3 ? Take the viscosity of air at the temperature of the experiment to be 1.8 xx 10^-5 Pa s. How much is the viscous force on the drop at that speed? Neglect buoyancy of the drop due to air.

A person trying to lose weight (dieter) lifts a 10 kg mass, one , thousand times, to a height of 0.5 m each time. Assume that the potential energy lost each time she lowers the mass is dissipated, (a) How much work does she do against the gravitational force? (b) Fat supplies 3.8 xx 10^7 J of energy per kilogram which is converted to mechanical energy with a 20% efficiency rate. How much fat will the dieter use up?

A first order gas phase reaction A_2B_2(g) rarr 2A(g)+2B(g) at the temperature 400^@C has the rate constant k=2.0xx10^(-4)sec^(-1). What percentage of A_2B_2 is decomposed on heating for 900 secs (antilog 0.0781=1.197)