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Specific Heat Capacity (S)

Definition: Amount of Heat required to increase or decrease the temperature by 1⁰C of 1 kg of body is called specific heat capacity.
It is denoted by 'S' and its unit is $\frac{J}{\mathrm{Kg⁰C}}$.
→ Specific heat capacity of water is maximum. i.e. S = 4200 $\frac{J}{\mathrm{Kg⁰C}}$.
Q. What do you mean by specific heat capacity of water is 4200 $\frac{J}{\mathrm{Kg⁰C}}$ ?
→ To increase temperature of 1 kg water by 1⁰C 4200J heat is required. Or to decrease temperature of 1 kg water by 1⁰C 4200J heat is to be extracted from it.

Water Sp. heat capacity S = 4200 $\frac{J}{\mathrm{Kg⁰C}}$.
Its Advantages are →
• It is used in vehicles engine to cool it.
• It is used in hot water bag to heat patient.
• It is used to patient of high fever as pad

Remember it.
• The temperature of object having high specific heat capacity increases or decreases slowly.
• The temperature of object having low specific heat capacity increases of decreases rapidly
• Same amout of heat is given to objects of same mass but different specific heat capacity then
  → the temperature of object of low Sp. heat capacity increase rapidly and have more temperature.
  → the temperature of object of high Sp. heat capacity increases slowly and have less temperature
  → but both object have same amount of heat energy.
• Two object of same mass but different Sp. heat capacity are heated to same temperature then
  → the object of low Sp. heat capacity have less heat energy.
  → the object of high Sp. heat capacity have more heat energy.
  → both object have same temperature.

Q. To cool engine of vehicle water is used, why?
→ Sp. heat capacity of water is maximum 4200 $\frac{J}{\mathrm{Kg⁰C}}$. So its temp. increases slowly. Fot this reason water is used to cool engine of vehicles.
Q. Water is used in hot water bag, why?
→ Due to high Sp. heat capacity of water it cools slowly. So that it is possible to heat patient for long time by once used hot water.
Q. In city near sea temperature is not so high or low, why?
→ In day time heat is absorbed by water, so temperature could not increase to high value. At night time water leave heat, so temperature could not drop too low. Thefore in city near sea is not too high or low temperature.
Q. At desert it too cold at night and too hot at day, why?
→ Sp. heat capacity of sand is low so it's temperature increases rapidly at day time so it hot in day but at night it's temperature decreases rapidly so at night it is so cold.
Q. Steam of water burn more to skin than boilling water, why?
→ Sp. heat capacity of steam of water is less than boiling water. So temperature of steam of water is high than boiling water which burn more to skin than boiling water.
Q. In cold season, steel chair is more coold than wooden chairs, why?
→ Sp. heat capacity of steel is less than wood. So steel's chair temperature decrease rapidly than wooden chair and feels us to steel chair more cold. → Steel is conductor of heat so when we sit on steel chair then heat transfer from our body to steel chair but it is not transfer in heat insulating wooden chair. So steel chair is more cold than wooden chairs
Q. Milk boils faster than water, why?
→ Due to low sp. heat capacity of milk than water, milk boils faster than water.

Do yourself

• Q. In a vessel 200gm sand and same another type vessel 200gm water is kept at same place for same time in shiny. After some time temperature is measured, it is found that temperature of sand is more than water, why?
  
• Q. Individually same amount of heat is given to 1kg water and 1kg mercury, whose temperature is more, why?
  
• ...
  

Q. Answer the following question using table.	Object	Sp. heat Capacity
	X	138 J/kg0C
	Y	380 J/kg0C
	Z	470 J/kg0C
Q. Equal mass of all three object are heated to same and leave in air to cool. Which one cool faster, why? → Object X cools faster because its least sp. heat capacity Q. To increase temperature of equal mass of all three objects up to same temperature, which one required maximum heat, why? → Object Z requires maximum amount of heat energy because of its high value of sp.heat capacity. Q. Equal mass of all three object are heated up to 2000C then put on wax slab. Which one penetrate maximum depth, why? → Equal mass of all three object are heated up to 200 0C then object Z has maximum heat energy because its high sp.heat capacity. Therefor object Z penetrate to maximum depth on wax slab. Q. To equal mass of all three object are given to same amount of heat energy, what happen the temperature of objects ? → To equal mass of all three object are given to same amount of heat energy, then temperature of object X increases faster and get maximum value and temperature of object Z increases slowly and get least value.

Q.Equal mass of three liquid are kept in three vessel of same type. Then these vessels are taken to shining day for same time, the temperature increase of liquid are given in table. Answer the following question.	Liquid	Increase in temperature
	A	80C
	B	60C
	C	40C
Q. Which liquid sp. heat capacity is maximum and why? → Liquid C has maximum sp. heat capacity because its temperature increased is least. Q. If given all three object are heated up to same temperature and left to cool then which one cools faster? → Liquid A cools faster, because which object heated faster, its minimum value of sp.heat capacity and that object also cools faster. Q. If given all three object are heated up to same temperature and left to cool then which one cools slowly? → Liquid C cools slowly, because which object heated slowly, its maxmum value of sp.heat capacity and that object also cools slowly.

Heat equation Q = m s dt
where, m is mass of object
s is sp. heat capacity of object
dt is change in temperature