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HEAT

      HEAT

There are mainly 4 scales of temperature :-
  1. Kelvin(K)
  2. Centigrade(*C)
  3. Fahrenhiet(*F)
  4. Reaumur(*r)

The relation between the following scales of temperature is as follows :

   *C -32 = K-273 = *F-32 = *r
         5           5              9        4


Heat energy is denoted by ‘Q’
Work is directly proportional to energy
So , W=JQ ( Here , J is the convergent factor whose value is equal to 4.18J/cal )
So we can also say that 1 cal = 4.18J


To test your understanding , here’s a small question :-
  1. If the amount of work done by a body is 20.9J , find the amount of heat energy produced
ANSWER :- 
By formula , 
                         W=JQ
 20.9 = 4.18 * Q
Q = 20.9/4.19
Q=5 calories 

See , it’s that simple ! Now let’s move on

THE CONCEPT OF SPECIFIC HEAT 

Specific heat is denoted by ‘C’
Heat energy is directly proportional to the mass of the object -1
Heat energy is directly proportional to the temperature difference – 2
By 1 and 2 , 
Q = m.C.dtheta

Where m – Mass
             C – specific heat ( constant )
        dtheta – delta theta ( this denotes the temperature difference )

Magnitude of C of water – 1 
 Magnitude of C of ice – ½

LATENT HEAT

As you all must be aware , latent heat is the amount of heat energy which is required by a particle to change it’s physical state
Q = m.L
Where Q=Heat energy
              m = mass of the object
              L = Latent heat 

L of ice ---- 80 cal(By default)

The Challenger Question :-
Science is nothing without application , and if you’re not able to apply what you’ve just learnt , then there’s absolutely no point in learning

Here’s a question for you , it isn’t that tough if you use your common sense

QUESTION :-
Container A :- 100g Water at 100*C
Container B :- 100g Ice at -50*C

If the water kept in Container A is poured into Container B , calculate the amount of ice which will melt as a result of this

I can sense that you’re a bit baffled , so here’s the solution , now try to understand

ANSWER :-
Heat energy of water = m.C.dtheta
                                                           = 100 * 1 * 100
                                                           = 10000 calories 
                 Total heat energy of ice = m.c.dtheta + m.L
                                                            = 100 * ½ * 50 + 100*80
                                                            = 2500 cal + 8000 cal

Now what we have to see is , this latent heat ( 8000 cal ) will be responsible for melting the ice
But , this 2500 cal of heat energy will be responsible for bringing the temp. of ice to 0*C ( it’s quite obvious )
Only after the temperature reaches 0*C , the ice will start to melt 
Therefore , heat energy of water which will melt the ice   = total heat energy of water – heat energy required to lower the temperature of ice
               = 10000 – 2500
               = 7500g

So , % of ice melted = 7500/8000 * 100
                                    = 93.8%
                    This translates to 93.8g

FINAL ANSWER :- 93.8g of ice will melt

You must surely be happy today , because you’ve learnt something new

Stay tuned for more scientific information 
I hope you liked today’s topic
  • Aryan Awasthi

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