Heat Transfer (physics)

HEAT TRANSFER

the study of heat flow within an object and from one object to another due to different temperature.

THREE FORMS :

1.RADIATIONHeat energy travels as electromagnetic waves

in the same manner and speed as light.

2. CONDUCTION

Heat energy travels when two objects at different temperature are in direct contract with each

other. During heat conduction, vibrating

atoms / molecules excite the atoms or molecules next to them.

3. CONVECTION

the heat fluids is transferred to cooler regions by current.

SPECIFIC HEAT

the amount of energy required to raise the

temperature of 1kg. of a substance by 1k.

J / KG. K = UNIT OF

MEASURE FOR SPECIFIC HEAT

HEAT / THERMAL CAPACITY

the amount of heat required to raise

temperature by 1 degree.

FORMULA :

Where:Q = amount of heat

transferredm = mass C = specific heatT = change in temperature

How much heat is needed to raise the temperature of 5kg of water 10 k?

Given:

m = 5kgC = 4180 J/kg.KT = 10 KQ = ?

Solution:Q = mC T = (5kg)(4180J/kg.k)(10 K)

= 209 000 J

• How much energy is lost by 10 kg of brass if it is cooled from 35 to 25 C?

38 500 J or about 9200 cal

• It takes 487.5 J to heat 25 grams of copper from 25 °C to 75 °C. What is the specific heat in Joules/g·°C?

c = 0.39 J/g·°C