1. Physics note
• Conduction ---conduction is the transfer of thermal energy without any flow of the
medium.
o Or, conduction is the transfer of thermal energy through a substance without the
substance itself moving.
• 2Oct. 12
mechanisms –molecular vibration and free electron vibration
• Solid [metals] are good conductors of heat while liquids and gases are poor conductors
of heat.
• Insulators---objects that cannot conduct heat well are called insulators
o Or, materials that are poor conductors of heat are called insulators. E.g. glass,
wood etc.
• Convection---it is the transfer of thermal energy by means of currents in the material
medium [liquid or glass]
o Or, convection is the transfer of heat through fluids [liquid or gas] by the upward
movement of warmer less dense regions of the fluid.
• Convection current ---Convection current is the movement of fluids caused by the
change in densities in various parts of the fluid.
• Radiation ---thermal radiation is the transfer of energy by infra- red [IR] waves.
o Or, radiation is the continual emission of infra – red waves from the surface of all
bodies, transmitted through space without the aid of material medium.
• Dull black surfaces are better emitters of infra – red radiation than shiny, white surfaces.
• The higher the surface temperature, the higher the rate of transfer of energy by
radiation.
• Work –work done by a constant force is given by the product of the force and the
distance moved in the direction of force
o Therefore, work done = force applied ×distance through the direction of the force
• [In joules, j] [In Newton, N] [In metre, m]
• Energy --- energy is the ability of a body to do work
Or, energy is defined as the capacity o9f a body to do work.
• Forms of energy ----
• Kinetic energy – this is the energy due to motion. All moving objects have kinetic energy.
• Potential energy –this is the energy which an object has because of its position, shape or state.
• Types of potential energy ---
• Gravitational potential energy --- this is the energy that an object possesses because of its
position above the ground.

2. Physics note
• Elastic potential energy --- this is the energy possessed by an stretched spring or rubber. Both of
them can do work when released.
• Chemical potential energy --- the energy stored in fuels, batteries, food etc is called chemical
potential energy. When they are burnt, they release energy by chemical reactions.
• Electrical potential energy --- electrons can transfer energy from a battery to a light bulb. They
Oct. 12
have electrical potential energy or electrical energy for short.
• Nuclear energy ---this is the energy released by the nucleus of an atom when the nucleus splits.
• Other types of energy ---
• Thermal energy—when hot objects cool down, their atoms and molecules slow down and lose
energy. This is known as thermal energy.
• Radiated energy – the sun radiates light. Loudspeakers radiate sound. Light and sound both
travel in the form of waves. These carry energy.
• Power -- powers defined as the rate of work done or energy converted.
in equation form,
• P = W/T = E/T
• One watt is defined as the rate of working or energy conversion of one joule
per second.
• DENSITY AND PRESSURE ---
• DENSITY --- the density of an object is its mass per unit volume
Density = mass ÷ volume
The SI unit of density is kilogram per cubic metre [kg/ m3]
• Pressure --- pressure is the force acting per unit area.
Pressure = force ÷ area
The SI unit for pressure is Pascal [Pa].
• Pressure increases with depth.
• The liquid will always settle to a common level.
The pressure at the base of a liquid column ---
P=ρ×g×h
• Where, p = pressure
ρ = density
g =gravitational field strength
h = height of the column
• Applications of transmission of pressure ---
• Hydraulic press.
• Hydraulic brakes.

3. Physics note
• SOLIDS LIQUIDS AND GASES ---
Properties
• solid • Fixed shape and volume
Oct. 12
• Normally hard and rigid
• High density
• Large force needed to change shape
• Particles of solid vibrate around fixed positions in the structure
• Have high melting and boiling points
• Strong intermolecular force of attraction between particles
• Incompressible
• Intermolecular space is minimum
• Liquid • Fixed volume but have no definite shape
• High density
• Not compressible
• Particles can move more freely than in solids
• Intermolecular space is greater than solids
• Weaker intermolecular force of attraction than solids
• Gas • No fixed shape or volume
• Low density
• Easily compressible
• Weak or no intermolecular force of attraction between particles
• Particles are free to move in any direction