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Heat content in an object depends on its type of material,

mass and temperature.

The heat capacity of an object is the quantity of heat energyrequired to increase its temperature by 1. Each object has

its own heat capacity.

The unit of heat capacity is J1 .

(when we are discussing the heat capacity, we DO NOT consider

about the mass factor!)

However , an object with a larger mass will have a large heat

capacity than an object with smaller mass of the same

material.

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Solehin places 2 pebbles of different masses and a glass ofwater under the hot afternoon Sun.

After 5 minutes, he finds that: The small pebble is hotter than the large pebble

The large pebble is hotter than water of the same mass.

sun

Water (samemass as thelarge pebble)Small

pebbleLargepebble

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The increase in temperature depends on:

The quantity of heat absorbed.

The mass of the object.

The material of an object.

Another example on the next page..

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5 J

5 J

1

If want to rise up 1must to absorb 5J ofheat capacity!

If want to rise down1 must to release5J of heat capacity!

10 J

10 J

1

If want to rise up 1must to absorb 10J ofheat capacity.

If want to rise down1 must to release10J of heat capacity.

Now, we can compare which one can easily to riseup the temperature and which one cant!!!!

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c = Q

m

Q = mc

Therefore the quantity of heat absorbedor lost by an object, Q = mc.

Specific heat capacity(J kg1 1)

Heat (J)

Temperaturechanges (/K)

(absorb / release)

Mass(Kg)

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5 J kg1 1

= 5J1kg X 1

If 1 kg of substance want to riseup 1 need to absorb 5J of heat.

If 1 kg of substance want risedown 1 need to release 5J ofheat.

10 J kg1 1

= 10J1kg X 1

If 1 kg of substance want to riseup 1 need to absorb 10J of heat.

If 1 kg of substance want to risedown 1 need to release 10J ofheat.

Caution: When we talk the temperature the mass must be constant.!!!!

Now, we can compare which one can easily to rise up thetemperature and which one cant!!!!

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900 J of heat needs to be supplied to 1kgaluminium to produce a 1C temperatureincrement.

1800J of heat needs to supplied to 2kgaluminium to produce a 1C temperatureincrement.

1800J of heat needs to supplied to 1kg

aluminium to produce a 2Ctemperatureincrement.

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Substance[solid]

Specific heatcapacity,c/ J kg1

C1

ICE (-15C) 2000

Wood 1400

Ceramic 1090Aluminium 900

Stone 840

Glass 753

Silicon 700

Steel 502Iron 452

Copper 387

Silver 235

Lead 130

Gold 129

Substance[liquid]

Specific heatcapacity,c/ J kg1

C1

Water(15) 4200

Ethanol 2450

Glycerine 2410

Parrafin 2100

Oil 1890

Benzene 1740

Mercury 140

Steam 2010

Human body 3500

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Heat Capacity Specific heatcapacity

Symbol C c

General unit Relates to a particular object:J C1

Relates to a material:J kg1C1

Value Not fixed, depends onthe mass of the object

Fixed for a materialregardless of its mass

Formula Q = C Q = mc

Relationship betweenc and C C = mc

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