Advertisements
Advertisements
प्रश्न
Why are athletes advised to put on extra clothes after competing on event?
Advertisements
उत्तर
Athletes perspire profusely after competing in an event. The latent heat of evaporation of the ‘sweat’ is withdrawn from the body itself and therefore, cools the body. Hence, if they do not put on extra clothes, they are likely to catch cold.
संबंधित प्रश्न
A child running a temperature of 101°F is given an antipyrin (i.e. a medicine that lowers fever) which causes an increase in the rate of evaporation of sweat from his body. If the fever is brought down to 98 °F in 20 min, what is the average rate of extra evaporation caused, by the drug? Assume the evaporation mechanism to be the only way by which heat is lost. The mass of the child is 30 kg. The specific heat of human body is approximately the same as that of water, and latent heat of evaporation of water at that temperature is about 580 cal g–1.
Heat supplied to a solid change it into liquid. What is this change in the phase called?
Name three fossil fuels that emit carbon dioxide into the atmosphere ?
A substance is heated at a constant rate from a low temperature to a high temperature. A graph of temperature against time is shown in the figure. Which part or parts of the graph correspond(s) to the substance existing in two states?
(b) 2000 J of heat energy is required to raise the temperature of 4 kg of a
metal by 3°c. Which expression gives the specific heat capacity of the metal?
The farmers fill their fields with water in winter. Give reason.
For a gas, `"R"/"C"_"v"=0.4`, where R Is universal gas constant and Cv is the molar specific heat at constant volume. The gas is made up of molecules, which are ______
Two uniform brass rods A and B of length land 2l and radii 2r and r respectively are heated to the same temperature. The ratio of the increase in the volume ofB to that of A is ____________.
Two blocks P and Q of different metals having their mass in the ratio 2 : 1 are given same amount of heat. Their temperature rises by same amount. Compare their specific heat capacities.
