Nota Fizik: Analysing scientific investigation

A variable is a quantity that can vary in value.

Manipulated variable is a variable that is set or fixed before and experiment is carried out. it is usually plotted on x- axis.

Responding variable is a variable that changes according to and dependent to manipulated variable. it is usually plotted on y-axis.

Fixed variable is fixed and unchanged throughout the experiment.

Inference: state the relationship between two VISIBLE QUANTITIES in a diagram or picture.

Hypothesis: state the relation ship between two MEASURABLE VARIABLES that can be investigated in a lab.

How to tabulate data?

-the name or the symbols of the variables must be labelled with respective units.
-all measurements must be consistent with the sensitivity of the instruments used.
-all the calculated values must be correct.
-all the values must be consistent to the same number of decimal places.

A graph is cosidered well-plotted if it contains the following:
- a title to shoe the two variables and investigation.
- two axes labelled with correct variables and units
- scales must be chosen carefully and graph must occupy more than 50% of the graph paper.
-all the points are correctly drawn.
-the best line is drawn.

Electromagnetic Spectrum

Electromagnetic Spectrum

When you watch television, listen to the radio or cook something in a microwave oven , you are actually using electromagnetic waves.

Electromagnetic waves are propagating waves in space with electric and magnetic components. These components oscillate at right angles to each other and to the direction of propagation.

Electromagnetic waves carries energy and momentum which may be imparted when they interact with matter.

Electromagnetic waves comprise of a series of waves whose frequencies and wavelengths extend over a broad range.

Waves in the electromagnetic spectrum vary in size from very long radio waves to very short gamma rays.

Visible light waves are the only electromagnetic waves we can see. We see these waves as the colours of the rainbow. Each colour has a different wavelength. Red has the longest wavelength and violet has the shortest wavelength. When all the waves are seen together, they make white light.

When white light shines through a prism or through water vapour, the white light is broken apart into the colours of the visible light spectrum.

The electromagnetic spectrum is the range of frequencies and wavelengths over which electromagnetic waves are propagated.

Sources of Electromagnetic Waves.

Matter is made up of elementary particles called atoms.

Every atom has a nucleus at its centre which is surrounded by orbiting electrons.

Electrons are charged particles and they move around the nucleus in orbits, each of which is a t a specific energy level. When a charged electron moves from an orbit with a particular energy level to one of a lower energy level, electromagnetic waves are emitted.

Electromagnetic waves are also produced when a charged particle (electron or nucleus) oscillates.

Properties of electromagnetic waves

Electromagnetic waves are:

a. Transverse waves
b. Do not require a medium to propagate and can travel in a vacuum.
c. The magnetic and electric field components of the wave oscillate at right angles to each other and to the direction of propagation of the wave.
d. Obey the wave equation c = fλ. c is the velocity of light, f is the frequency of the wave and the λ is the wavelength.
e. In a vacuum , the waves travel at the speed of light c = 3 X 10^8 ms-1.
f. Undergo the same phenomena as light: reflection, refraction, diffraction and interference.
g. The waves are electrically neutral.
h. Show characteristics of polarization.
i. Energy is transferred by the waves.

In a vacuum, c is a constant for all elecgromagnetic waves The formula c = fλ shows that the frequency f is inversely proportional to the wavelength λ.

The velocities of an electromagnetic wave in other media are different from its velocity in vacuum.

Applications of Pascal's Principle in Everyday Life

A hydraulic system is a device in which a small applied force can give rise to a larger force.

The principle in the hydraulic system is widely used in jacks, vehicle brake systems, hydraulic presses and heavy machinery.

Hyraulic Jacks
Hydraulic jacks are used to lift a heavy load such as when changing a car tyre. When the handle is pressed down, a valve closes and the small piston forces hydraulic fluid through another valve to the larger cylinder. The pressure transmitted results in a large force on the load.


When the handle is raised, valve B closes and hydraulic fluid flows from the buffer tank through valve A into the small cylinder. The handle is moved up and down repeatedly until the load is sufficiently lifted up.

The large piston can be lowered at the end by opening the release valve to allow all the hydraulic fluid to flow back into the buffer tank.

Hydraulic Brakes

Hydraulic brakes are used in cars, lorries and motorcycles.

In a hydraulic brake system, a liquid, known as brake fluid,
is used to transmit pressure from the brake pedal to all the wheels of the vehicle.

When the brake pedal is pressed, the piston of the control cylinder applies a pressure on the brake fluid and this pressure is transmitted, via a system of pipes, to each cylinder at the wheels.

The cylinder at the wheels cause a pair of pistons to push a pair of friction pads to press against the surface of the brake discs or brake drums. The frictional forces between these brake components cause the vehicle to slow down and stop.

When the brake pedal is released, a spring restores the brake discs to their original positions.


Hydraulic Pumps

Hydraulic pumps are used to raise cars in a motor workshop.

The machine is equipped with a small cylinder connected to a large cylinder. Both cylinders are filled with oil.

Compressed air is introduced into the small cylinder in which the compressed air exerts a pressure on the surface of the oil.

This pressure is transmitted by the oil to the large cylinder where the pressure acts on a large piston to produce a force which is large enough to lift a car.

Nota Fizik: Analysing scientific investigation

A variable is a quantity that can vary in value.

Manipulated variable is a variable that is set or fixed before and experiment is carried out. it is usually plotted on x- axis.

Responding variable is a variable that changes according to and dependent to manipulated variable. it is usually plotted on y-axis.

Fixed variable is fixed and unchanged throughout the experiment.

Inference: state the relationship between two VISIBLE QUANTITIES in a diagram or picture.

Hypothesis: state the relation ship between two MEASURABLE VARIABLES that can be investigated in a lab.

How to tabulate data?

-the name or the symbols of the variables must be labelled with respective units.
-all measurements must be consistent with the sensitivity of the instruments used.
-all the calculated values must be correct.
-all the values must be consistent to the same number of decimal places.

A graph is cosidered well-plotted if it contains the following:
- a title to shoe the two variables and investigation.
- two axes labelled with correct variables and units
- scales must be chosen carefully and graph must occupy more than 50% of the graph paper.
-all the points are correctly drawn.
-the best line is drawn.

Applications of Bernoulli's Principle

 The flight of an aeroplane is based on the principle about the effect of the flow of air around its wings, which is, the aerofoil.
- An aerofoil shape has a rounded front edge and pointed (sharp) trailing edge. The top surface is arched (curved) and the bottom is flat.
-When a wing in the form of aerofoil moves through air, the flow of the air over the top has to travel faster to cover the longer distance (compares the lower portion) and creates a region of low pressure. The flow of air below the wing is slower resulting in a region of higher pressure.
-The difference between the pressures at the top and the bottm creates a NET UPWARD FORCE..(remember! bottom part higher pressure..upper part lower pressure).This is called a Lift and helps the plane to take off.
-In addition to that, inverted aerofoils are used in racing cars to create a donward force and stabilize the cars at high speed.

2. Bunsen Burner

- When a bunsen burner is connected to a gas supply, the gas flows at high velocity through a narrow passage in the burner, creating a region of low pressure.
- The outside air, which is at atmospheric pressure, is drawn in an mixes with the gas.
-The mixture of gas and air enables the gas to burn completely to produce a clean, hot fire.

Other applications that you must read on your own.

- Hydrofoil Boat
- Insecticide Spray (or whatever sprays that available)
- The shape of canvas roof ( in car) when its moving - why the roof bulges upward?
- Carburettor
- Curve Ball Spin offs
- The shape of a ski-jumper's body when he's jumping..its curved right? Why?

All the best

What is Physics?

What is Physics?

Physics is a branch of science which studies physical and natural phenomena around us.

Examples of natural phenomena are formation of rainbow, solar eclipse, the fall of things from up to down, the cause of sunset and sunrise, formation of shadow and many more.

Physics mostly answers whys rather than what and it gives scientific, systematic and consistent explanation based on the concepts of physics.

Physics knowledge will increase as the flow of time; new concepts will replace old concepts if proven to be accurate.

The word physics evolved from ‘physikos’ a Greek word for nature.

There are two main divisions of physics which are:
a. Classical physics: motion and energy, mechanics, force and motion, heat, sound, electricity, magnetism and light.
b. Modern physics: atomic, molecular and electron physics, nuclear physics, relativity, origin of universe, astrophysics.

Topics learnt in form 4 are:

1. Introduction to physics
2. Forces and motion
3. Forces and pressure
4. Heat
5. Light



Topics in form 5 would be:

1. Waves
2. Electricity
3. Electromagnetism
4. Electronics
5. Radioactivity

Several discoveries and contributions based on the knowledge of physics:

1911 –New Zealand-born British physicist Ernest Rutherford (UK, New Zealand), proposed that an atom has a positively charged nucleus called Proton.
1957 –Sputnik I, first satellite to orbit the earth (Soviet Union).
1969 –Man landed on the moon – Neil Armstrong became the first human being to set foot on the moon (US).
1989 –www was launched by British Engineer Tim Berners-Lee and his colleague (UK).
1990 –The Hubble Space Telescope was built and launched into orbit by NASA (US).

Among the important figures in Physics:
Galileo Galilei
Isaac Newton
Charles Augustin de Coulomb
Albert Einstein
Stephen William Hawking

Study of Physics

1. As the other branches of science, scientific skills is necessary in the process of undertaking research and analysis in physics.

2. Research or Experiments are done systematically and step by step based on scientific method.

3. Scientific method

Identifying Problem ---- Making Hypothesis -----Planning investigation ------Identifying and controlling variables ----conducting experiment ----collecting data ----recording data----making conclusions---writing reports.


Careers in Physics included (examples)
1. Engineering
2. Computer Science
3. Industry
4. Communication
5. Electronics
6. Medicine – X ray
7. Environmental Science
8. Basic Research

Uses of Gas Laws

1.Bicycle Pump

When the piston is pushed into the cylinder, the air in the cylinder is compressed.

According to Boyle's Law, the air pressure inside the cylinder will increase.

This causes the air pressure in the cylinder to become higher than the pressure inside the tyre. Therefore, the air can flow into the tyre.

2. Hot-air baloon

When the air in a balloon is heated at atmospheric pressure, its temperature will increase.

According to Charles' Law, the volume of gas in the balloon will increase when its temperature increases.

Thus, the upward thrust on the balloon will increase when the volume of air displaced by the balloon increases.

Therefore, the balloon will climb upwards if the upward thrust exceeds the weight of the balloon.

3. Car Tyre

When a car is moving, the car tyre will experience frictional force and compression. This condition causes the temperature of the air inside the tyre to increase.

According to the Pressure Law, the rise in tyre temperature will cause the pressure inside the tyre to increase until an optimum level. Therefore, it is wise to pump the tyre just slightly below the recommended level. Anyway, we must also adjust the pressure of the tyre according to the temperature when we pump the tyre.