Happy New Year 2010

Each moment in a day has its own value.
Morning brings HOPE,
Afternoon brings FAITH,
Evening brings LOVE,
Night brings REST,
Hope you will have all of them everyday.
HAPPY NEW YEAR 2010.

Solar Cooker

Application of curved mirror.

Watch the video.

Find out more :
1. Why do they use dull black pot instead of white shiny pot ?
2 Where is the pot located ?
3. Are you able to draw ray diagram to show principle focus of the mirror?

Curved Mirrors

A curved mirror is a section of a sphere.
If the outside surface of the sphere is reflecting, the mirror is convex.
If the inside surface is reflecting, the mirror is concave.

The characteristics of the image formed can be
i. real or virtual
ii. inverted or upright
iii. larger , smaller or the same size of the object
By drawing ray diagrams, you can find out how the image would be.


Ray diagram --concave mirror1. Draw ray from top of object to the curved mirror. After reflecting off mirror, the ray passes through the focal point. (Purple ray)
2. Draw a ray from the top of the object through the focal point. The ray will be parallel to the optical axis after reflecting. (Green ray)
3. Draw the image as a vertical arrow with its tail on the principle axis and the head at the point where the two reflected ray meet.

Tips: Images formed "behind" the concave mirror are always upright and virtual.

Ray diagram --convex mirror


1. Draw ray parallel to optical axis. After reflection, this ray travels as if it is coming from the far focus. (Purple ray)
2. Draw line from top of object to centre ,C (Red ray).
3. The virtual image is drawn using a dotted line with an arrow.

Tips: Images formed by a convex mirror are always smaller that object.
Hand on :
Take the standard steel spoon in your kitchen, observe images formed at both side of the spoon at difference distance. What can you say about the image formed?

Reflection of light

Reflection occurs when a light ray bounces off a surface.

Terminology :

Incident ray is the incoming light ray.

Reflected ray is the light ray moving away from the surface .

The most important characteristic of these rays is their angles in relation to the reflecting surface. These angles are measured with respect to the normal of the surface.

The normal is an imaginary line perpendicular to the surface.

The angle of incidence, θi is measured between the incident ray and the normal.

The angle of reflection, θr is measured between the reflected ray and the normal.

When a ray of light is reflected, the reflected ray lies in the same plane as the incident ray and the normal.

Law of Reflection
The Law of Reflection states that the angles of incidence and reflection are always equal and
that the reflected ray always lies in the plane of incidence.

When you smile into a mirror, you see your own face smiling back at you. Did you notice that;
i. the size of the image is the same as you (object)
ii. the distance of the image seem as the same distance of you from the mirror.
iii. when you move your left hand, the image will move it right hand
iv. then you image never upside down .



worked example:
Question: An incident ray strikes a smooth reflective surface at an angle of 33◦ to the surface normal. Calculate the angle of reflection.

Answer
Step 1 : Determine what is given and what is required We are given the angle between the incident ray and the surface normal. This is the angle of incidence. We are required to calculate the angle of reflection.

Step 2 : Determine how to approach the problem We can use the Law of Reflection, which states that the angle of incidence is equal to the angle of reflection.

Step 3 : Calculate the angle of reflection We are given the angle of incidence to be 33◦. Therefore, the angle of reflection is also 33◦.

quiz :

Laws of reflection » Quiz Make

Is light rays real ??

In physics we use the idea of a light ray to indicate the direction that light travels. Light rays are lines with arrows and are used to show the path that light travels.


The most important thing to remember is that we can only see an object when light from the object enters our eyes. The object must be a source of light (for example sun) or else it must reflect light from a source (for example the moon), and the reflected light enters our eyes.


Light rays are straight lines with arrows to show the path of light.
Important: Light rays are not real. They are merely used to show the path that light travels.

Did you still remember, light travel in straight line?

Formation of shadows is the evidence that light travel in straight line.



Test Quiz

1. Are light ray real ? Explain.
2. Give evidence to support the statement:" Light travels in straight lines". Draw a ray diagram to prove this.

Merry X'mas

Ripple tank.

Ripple tank

A ripple tank is a shallow glass tank of water used in schools to demonstrate the basic properties of waves. The tank is illuminated from above, so that the light shines through the water.
The ripples on the water show up as shadow on the screen underneath the tank.
All the basic properties of waves can be demonstrated.


A stroboscope, also known as a strobe, is an instrument used to make a moving object appear to be slow-moving, or stationary.




Source http://commons.wikimedia.org/wiki/File:Simple_ripple_tank.svg



The water acts as a lens to produce a pattern of bright and dark regions on the screen (or a piece of white paper).

Understanding base quantities and derived quantities

Physical quantities are quantities that can be measured. They can be classified into:
(i) Base quantities
A base quantities is a quantity that cannot be expressed in terms of other quantities.

(ii) Derived quantities

A derived quantity is a quantity that is a combination of base quantities by meant of multiplication, division or both.

To make working with units easier, some derived units are given special names.


It is very important that you are able to recognise the units correctly. For instance, the new- ton (N) is another name for the kilogram metre per second squared (, while the kilogram metre squared per second squared ( is called the joule (J).

Lesson review :

1. Explain what base quantities and derived quantities are.
2. list 5 base quantities and their units
3. list 5 derived quantities and their units.

Base quantities and derived quantities » Make Your Own Quiz

Capacitors

Capacitors are devices used to store electric charge and usually involve conducting plates separated by an insulator. (One plate is positive while the other is negative.)

When the capacitor is connected to a battery, electrons flow from the negative terminal to plate


Capacitors are widely used in electronic circuits to block the flow of direct current (D.C) while allowing alternating current(A.C) to pass, to filter out interference, to smooth the output of power supplies, and for many other purposes.

SPM past year questions:
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related video from http://ec.europa.eu/research/mariecurieactions/

Physics Definition

Normally this is test in paper 2 and 3, remember to answer in full sentence DO NOT write equation !!!
example :
a. ) momentum is product of mass and velocity ( correct )
b. ) momentum = mass x velocity ( wrong)
SPM Physics Terms and Definition

How to answer SPM physics (paper 2 and 3)?

Semua maklumat yang diberi adalah dari JUJ Pahang 2009.

1. How to write experiment precaution ?

prec

2. Tips to answer paper 2

p2

3. Tips to answer paper 3

D Desktop g3

Tips for paper 2 ( SPM physics)

1. Definition of the term in Physics
Force, work, inertia, impulsive force, coherent...

2. The principle in Physics and applications
Force in equilibrium, thermal equilibrium, Pascal's principle, conservation of momentum.

3. The Law in Physics and application
Hooke's Law, Ohm's Law, Boyle's Law, Charles Law

4. Graph skills
Axis, plotting, scale, straight or curve line, gradient, extrapolation.

5. Drawing skills
Total internal reflection, lens ray, inteferens, field circuit, refraction of wave



Mini quizzes :
1. What is meant by frequency of oscillation on spring?
2. What is meant by pressure ?
3. Define speed.


4.

How to answer paper 1 (SPM Physics)

SPM at the corner already , it time to refresh some common exam tips. One way

1. Cancel or mark (x) which is wrong option then choose.
   
2. Always refer to the formula given on page 2
3. Blacken each finished answer immediately.

Example:
1.










2.

Displacement- time graph

What to learn in this unit?
1. plot and interpret displacement-time graphs.
2. determine distance, displacement and velocity from a displacement-time graph
3. deduce information from the shape of a displacement-time graph

Content :
On a displacement-time graph, the gradient of the graph is numerically equal to the velocity of the object.

a.On a displacement-time graph, a horizontal line (gradient = ________ ) shows that an object s stationary.
Object moving with constant velocity
Object moving with increasing velocity.
Object moving with decreasing velocity.

The Equation of linear motion

The equations of linear motion is apply to bodies moving linearly with uniform acceleration .
There are 5 variables in the equation
v = final velocity,
u = initial velocity,
s = displacement,
a = acceleration,
t = time


You should be able to solve problems using equation about.

Example :
1. A cyclist accelerates uniformly at 1.2 ms-² in 10 s from rest. What is his displacement at this time?

Tips:

• Rest mean zero velocity !!
• You need to know 3 variables to find out the required quantities .
  

Suggested solution
Given;

u = 0 ms-¹
a = 1.2 ms-²
t = 10 s
v = ? ( since v is not given you are unable to calculate s using equation 1, 2, 4 and 5)

substitute all given information into equation 3
s= ut+ 1/2 at²
s= (0) (10) + 1/2 (1.2) (10)²
=60 m (very often, student forget to mention the unit. )


2. A car approaches a traffic light at 15m/s. The traffic light turns red and the driver applies the brakes at the distance of 25 m from the junction and decelerate at 5 ms-². Can the car come to complete stop before reaching the stop line at the traffic light? (ans : yes)

Tips:

• remember to insert the negative sign (-) for decelerate

*learn more in http://en.wikipedia.org/wiki/Equations_of_motion

Last minutes SPM physcis check list

5UM and 5 UKM students pls download.
Fill in the blank i will discuss with you all after 2nd trial.
All the best ...good luck in your coming SPM

tip jawab

Acceleration and deceleration

Dear our form 4 students answer following question before star your lesson.

Pretest:

1. state the meaning and unit for the symbol
i) a
ii) v
iii) u
iv) t

2. Define acceleration and deceleration

Lesson start:

Acceleration is the rate of change of velocity. ( 1 mark in paper 2 )

An object accelerates when it moves with increasing velocity.

An object decelerates when is getting slower, its velocity is decreasing.

Equation :

where

a: acceleration ( ms-²)

u: initial velocity ( ms-¹)

v: final velocity ( ms-¹)

t: time ( second)

Calculation:

Tips:

First of all find out all useful info as highlighted. Then substitute the info given in equation, while you are calculating check whether need to change units or not. (e.g., from km to m, hour to seconds)

email your solution to fizikf5@gmail.com

1.An athletic runs from the starting line and achieves a velocity of 12 m/s in 3 s. Find his/her acceleration. (ans: 4 ms^-2)

2. A track travels along a road with a velocity of 20 m/s the driver slam on the brake when a chicken suddenly runs across the road. Assuming the truck take 8s to complete stop from the time the driver hit the brake, determine the acceleration of the lorry. (ans: -2.5 ms^-2)

3. A motorcycle move with a velocity of 25 m/s. the motorcyclist brakes and its velocity decreases uniformly to 10 m/s in 3s. The motorcycle continues to slow down with the same acceleration until it comes to a stop. Find the time taken for the motorcycle to stop. (ans: 5s)

* Step 1 : Determine its acceleration in the first 3s,

Step 2 : Determine the time taken .

For more detail study the graph below.

Physics Trial SPM 2009

1. Perak [paper 1], [paper 2], [ paper 3], [answer]
2. Johor [paper 1], [paper 2], [ paper 3], [answer]
3. Sabah [paper 1], [paper 2], [ paper 3], [answer]

Jadual SPM ditukar lagi

This is version 09/09/09 by LPM. Hopefully this version will be last until SPM 2009 end.
JadualWaktuSPM0909

Form 4 Chapter 3 Force and pressure

Simple notes and exercises with answer

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