Hari Kumar R

Krishna Kumar R

Sangeetha R

Saravanan A

Sruti B

Task 1

CONDUCTIONPop corn cooked with oil in a panOil conducts heat

CONVECTIONPop corn cooked in a popperAir transfers heat

RADIATIONPop corn cooked in a micro-wave ovenMicrowaves break down the bonds

Method Conduction Convection Radiation

Steaming High High Low

Boiling High Moderate Low

Deep frying High Moderate Low

Sautéing High Low Low

Broiling Moderate Low High

Baking High High Moderate

Grilling Moderate Moderate High

Microwaving Low Low High

PERSPIRATIONAmbient temp > body tempEvaporation occursCooling effect of perspiration is due to large

heat of vaporization of water Heat of vaporization = 580 cal/g

CONDUCTION

CONVECTIONHeat transfer medium: air surrounding the

body

Air motion will remove heat from the skin

Increase of heat transfer to the air

Loss due to convection calculated by correlating with loss due to conduction

Conduction and convection together are not adequate for cooling

RADIATION

Cold blooded animals come out in summerTherefore, there are more of insects and

reptiles in the equatorial regionElephant ears act like giant radiators to

transfer heat out of their bodies.

When fans rotate in forward direction It blows the cool air downCan be used in summer

When fans rotate in the reverse directionMakes hot air rise and gently mixes the airCan be used during winter

Hair is partially wetted Oil applied is the conducting medium A metal pressing comb is heated to 300-

500oF The high temperature breaks down the

biochemical disulphide bonds between the keratin proteins

As the hair cools, the broken bonds are fixed in the required shape

This reformation of the bonds holds the hair in its new, straightened shape

A coil of wire is placed beneath the cooking surface

A large ac current is made to flow through the wire

Hence an oscillating magnetic filed is set up

This field induces an electric field when a metal is brought into contact

The eddy resistance in the metal is converted to heat

Coolant is pumped through radiators The radiator transfers the heat from the

fluid inside to the air outside, thereby cooling the engine

Air cooled engines use the air blowing past the engine

But long stationary periods may cause over-heating

Air cooled bikes are cheaper, simpler and lighter than their water-cooled counterparts

Cold water remains at the bottom of the tank as it is denser than hot water

When you first put the water in the coffee maker, the heating element heats it.

Once the coffee is made, the heating element keeps the coffee warm.

Clay is a mixture of mud and water The wet clay pot is heated so that all the

moisture in the wet clay is taken out completely

The whole material is purely porous with very fine holes all over

When you pour water of any temperature more than the room temperature into the pot, the water first spreads itself on to the walls of the pot

Due to the internal pressure of water, the water is forced to contact to the pot inner walls. So the water molecules start filling the air gaps of the pot

In this condition, due to the very fine holes, the water molecules lose their contact and forms in to separate groups of water particles

Since the water volume is very less, it tends to go away from the pothole, and for that is has to be converted in to vapor state. But the temperature of the water is not enough to change its state from liquid to gaseous