HEAT
The definition of heat
Heat is a form of energy transferred from the hotter object to the colder one
Example :
Hot iron dipped into a glass of cold water, few minutes later the water’s temperature will
increase, while the iron’s temperature will decrease.
1. The effect of heat on mass of matter
l Quantity of heat is proportional (linear) to the mass of a matter
Q ~ m
Q = heat (Joule or Calory)
m = mass of matter (kg)
2. Heat is proportional to the spesific heat of matter
Quantity of heat depends on the nature of the materials
Q ~ c
Q = heat (Joule or Calory)
c = specific heat of matter (J/kgoC)
3. The effect of heat on temperature of matter
The greater the quantity of heat trensferred to the matter, the greater the rise in the matter’s temperature
Q ~ ΔT
Q = heat (Joule or Calory)
ΔT = the temperature change (oC or K)
So the quntity of heat (Q) required to increase the temperature of a metter depends on the mass (m), specific heat (c), and the temperature change (ΔT)
Q = m c ΔT
Q = quantity of heat, (J)
m = mass of matter (kg)
c = specific heat of matter (j/kgoC)
ΔT = the temperature change (oC or K)
Conclution:
The amount of heat transferred by an object depends on several aspects, such as mass, materials type (specific heat of matter), and the amount of temperature changes.
Exercise heat 1:
What is the heat requered to increase the temperature of 4 kg of iron from temperature of 20C to be 60C? (the specific heat of iron is 460 J/Kg C)
Answer : Q = 73.600 J
Heat Capacity
Heat capacity is defined as the quantity of heat needed to raise the temperature of a body by 1oC. Mathematically formulated as
C = Q/T
Q = the quantity of heat (J)
C= heat capacity (J/oC or (J/K)
T = the temperature change ( oC or K)
From 2 formula above, we can conclusion
C = c m
C = heat capacity (J/oC or (J/K)
c = specific heat of matter (j/kgoC)
m = mass of matter (kg)
Heat Capacity: C = Q/ ΔT or/ atau C = m.c
C= heat capacity (J/C atau J/K)
Q = the amount of heat required or released (J)
m = massa (kg)
c = specific heat ( J / KgC atau J / KgK)
Exercise Heat Capacity
Heat of 50.000 J can increase the temperature of the body from 10C until 30C. What is the heat capacity of the body?
Answer : C = 2.500 J/ C
