Question

Give reason:
(a) Water droplets appear on the outer surface of a tumbler containing ice cold water.
(b) On a hot sunny day, people sprinkle water on the roof or open ground.

Answer 1

Hint: The above problem can be resolved using the concepts of vaporisation and the thermal energy interaction within the various states of matter. Moreover, the effect of heat transfer from one system to the other system, to cause the cooling effect can be applied to obtain the conclusion for the given set of conditions.


Complete step-by-step solution
(a) The water droplets appear on the outer surface of a tumbler containing ice cold water. This is because due to the interaction of thermal energy between one state to another state of matter. As the molecules of water vapour present in the air come in contact with the tumbler containing the cold water, it begins to release some amount of thermal energy. Due to this the vapours get converted to liquid state and appear in the form of water Droplets.

(b) On a hot sunny day, the people usually sprinkle water on the roof or open ground because when water is sprinkled on the roof, it absorbs the thermal energy in the form of heat. This causes the sprinkled water, and lower down the temperature of the roof to create some cooling effect.


Note: In order to resolve the given condition, one must be aware of the basic concepts of thermal energy transfer and heat interaction within the system and surrounding. Moreover the key concepts and fundamental laws of thermodynamics, along with concepts of evaporation, condensation etc. can help to conclude the given condition.