Calorimetry Physics - Calorimetry

A calorimeter is kept in a wooden box to insulate it thermally from the surroundings. Why is it necesaary?

What is the specific heat capacity of:

1. Melting ice
2. Boiling water?

The atmospheric temperature in the cities on sea-coast change very little. Explain.

When a solid melts or a liquid boils, the temperature does not increase even when heat is supplied. Where does the energy go?

Four 2cm × 2cm × 2cm cubes of ice are taken out from a refrigerator and are put in 200ml of a drink at 10°C.

1. Find the temperature of the drink when thermal equilibrium is attained in it.
2. If the ice cubes do not melt completely, find the amount melted. Assume that no heat is lost to the outside of the drink and that the container has negligible heat capacity. Density of ice = 900kg-m^-3, density of the drink = 1000kg-m^-3, specific heat capacity of the drink = 4200Jkg^-1-K^-1, latent heat of fusion of ice = 3.4 × 10⁵J-kg^-1.

Is heat a conserved quantity?

A block of mass 100g slides on a rough horizontal surface. If the speed of the block decreases from 10ms^-1 to 5ms^-1, find the thermal energy developed in the process.

A van of mass 1500kg travelling at a speed of 54kmh^-1 is stopped in 10s. Assuming that all the mechanical energy lost appears as thermal energy in the brake mechanism, find the average rate of production of thermal energy is cals^-1.

A person's skin is more severely burnt when put in contact with 1g of steam at 100°C than when put in contact with 1g of water at 100°C. Explain.

Indian style of cooling drinking water is to keep it in a pitcher having porous walls. Water comes to the outer surface very slowly and evaporates. Most of energy needed for evaporation is taken from the water itself and the water is cooled down. Assume that a pitcher contains 10kg of water and 0.2g of water comes out per second. Assuming no backward heat transfer from the atmosphere to the water, calculate the time in which the temperature decrease by 5°C. Specific heat capacity of water = 4200J kg^-1°C^-1 and latent heat of vaporization of water = 2.27 × 10⁶ J kg^-1.

The temperature of an object is observed to rise in a period. In this period:

1. Heat is certainly supplied to it.
2. Heat is certainly not supplied to it.
3. Heat may have been supplied to it.
4. Work may have been done on it.

The ratio of specific heat capacity to molar heat capacity of a body:

1. Is a universal constant.
2. Depends on the mass of the body.
3. Depends on the molecular weight of the body.
4. Is dimensionless.

The heat capacity of a body depends on:

1. The heat given.
2. The temperature raised.
3. The mass of the body.
4. The material of the body.

When a hot liquid is mixed with a cold liquid, the temperature of the mixture:

1. First decreases then becomes constant.
2. First increases then becomes constant.
3. Continuously increases.
4. Is undefined for some time and then becomes nearly constant.

Which of the following pairs represent units of the same physical quantity?

1. Kelvin and joule.
2. Kelvin and calorie.
3. Newton and calorie.
4. Joule and calorie.

The temperatures of equal masses of three different liquids A, B and C are 12°C, 19°C and 28°C respectively. The temperature when A and B are mixed is 16°C, and when B and C are mixed, it is 23°C. What will be the temperature when A and C are mixed?

An aluminium vessel of mass 0.5kg contains 0.2kg of water at 20°C. A block of iron of mass 0.2kg at 100°C is gently put into the water. Find the equilibrium temperature of the mixture. Specific heat capacities of aluminium, iron and water are 910Jkg^-1-K^-1, 470Jkg^-1-K^-1 and 4200Jkg^-1-K^-1 respectively.

A piece of iron of mass 100g is kept inside a furnace for a long time and then put in a calorimeter of water equivalent 10g containing 240g of water at 20°C. The mixture attains and equilibrium temperature of 60°C. Find the temperature of the furnace. Specific heat capacity of iron = 470J kg^-1°C^-1.