What is heat?
In summer you drink cold water daily, in contrast, in winter you drink hot coffee. Why in hot you drink cold liquid and in cold you drink hot?
The answer is heat and Its transfer.When you drink cold water you transfer heat from your body to the liquid, similarly when you drink coffee, you transfer heat from liquid to body.
But what is the heat?
First we define heat in 3 ways and then explain it.
Definition#1 "the transfer of energy between two or more objects because of temperature difference between them"
Definition#2"the total translation kinetic energy of the molecules of a substance is called heat"
Definition#3"Heat is thermal energy in transit"
Explanation: Unit the middle of 19th century many scientists believed that heat was an actual a substance called caloric which means invisible but later it was discovered that heat is not a substance, but transfer of energy between two or more objects.
It is denotes by Capital letter Q.
Units:The SI unit of Heat is Joule and Conventional or Biological unit is Calorie.
Joule:One joule is defined as
"the amount of energy required to displace a body or particle through a distance of 1m, by a force of 1newton".
Calorie:"The amount of heat required to raise the temperature of 1kg of water by 1 degree Celsius at 1atm pressure".
Relation between Joule and Calorie
1calorie=4.184Joules
Important point:Colorie is larger unit than than Joule because 1 calorie is equal to 4.184 joules
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