Heat(FORM 1)
7.2 Heat Flow and its Effect
a) Heat flows from a hot region to a cold region
b) Heat flows in three ways.They are conduction, convection and radiation.
CONDUCTION
a) Conduction is the flow of heat through a solid due to a difference in temperature throughout the solid
b) Conduction in a solid takes place through the vibration and collision of its particles.
c) Salin muka surat 112(figure 7.10)
CONVECTION(perolakan)
a) Convection is the process of flow of heat in a fluid(bendalir).
b) A fluid is a substance that can flow such as water and air. It carries heat along when flowing from one area to another.
c) Similar to solid, the fluid also allows heat to flow from a hot area to a cooler area.
d) Convection occurs faster if there is a greater difference in temperature in the fluid
e) Salin muka surat 114(activity 7.8)
f) Salin muka surat 115(activity 7.9)
RADIATION(sinaran)
a) The process of flow of heat by an illuminated object is called radiation.
b) Heat which is transferred is known as radiant heat.
c) Radiation is the process of energy flow through infrared waves.
d) Radiation does not need any medium.Radiant heat can travel through a vacuum(space without any matter)
e) Salin muka surat 116(semua)
f) Salin muka surat 117 Tulis tajuk: Heat Flow in natural phenomena (figure 7.19 & 7.20)
7.3 The Effect of heat on matter
# The change in state of matter takes place through physical processess such as melting, boiling, freezing,evaporation, condensation and sublimation.
Salin figure 7.22(ms 121)
Salin Table 7.4(ms121)
a) Melting(Peleburan)
i. Solid change into liquid.
ii. When solid is heated, the particles absorb heat energy.
iii. The heat energy causes the particles to vibrate more vigorously.
iv. Particle move further apart.
b) Freezing(Pembekuan)
i. Liquid changes into a solid
ii. A liquid turns into a solid when cooled to a certain temperature.
iii. The particles release heat energy to the surrounding.
iv. The particles of liquid move slower and the particles get closer together.
v. The temperature at which a liquid freezes into a solid is constant. This temperature is called freezing point.
vi. The freezing point of water is 00 C.
c) Boiling(pendidihan)
i. Liquid changes into a gas
ii. The temperature of a liquid at the point of boiling is constant. This temperature is called boiling point.
iii. The particles absorb heat energy
iv. At the boiling point, the liquid particles will gather enough energy to break free from the liquid.
v. The boiling point of water is 100 0C, water turns into steam at its boiling point.
vi. Salin figure 7.24(ms 122)
d) Condensation(kondensasi)
i. Gas(steam) changes into a liquid.
ii. When gas is cooled, its particles release heat energy to the surrounding.
iii. As gas particles move slower and closer together, a liquid will be formed.
e) Evaporation(penyejatan)
i. Liquid changes into gas at any temperature below its boiling point.
ii. The particles at the surface of a liquid absorb heat energy from the surrounding.
iii. Salin figure 7.25(ms 123)
f) Sublimation(pemejalwapan)
i. Solid changes directly into gas without melting and vice versa.
ii. In this process, the particles of a solid absorb heat energy. When enough energy is absorbed, the particles separate to form gas.
iii. Salin figure 7.26(ms123)
