Took the photos and created this slideshow especially for 2A~
Please look at this slideshow and answer Q1, Q2, Q3 and Q4:
Leave a comment in this entry with your answers.
In the "Post a comment" box, type in the answers in sequence.
Q1:
Q2:
Q3:
Q4: (it will be good to show me the working)
If you still don't know how to comment here, you may send your answers to me via a message in Facebook instead.
Regarding Q1 about the cross-section, recall Q2 of your workbook, which was just covered on Friday morning for most of you.
Please comment before your 1-week term break ends. =)
As promised, if your 4 answers were all correct and they're submitted before the deadline, you'll receive an awesome sweet from me~!
28 August 2010
Surface area for 2A
26 August 2010
22 August 2010
Moments in daily life
Moments = Turning effects of forces
It's helping us everyday in more ways that we can possibly count... your door on hinges, your spoon as a lever to open your tin can, your foldable tables and chairs, flipping open your laptop, even flipping open your books and folders etc... it's all about turning effects of forces.
Transmission of heat
This is for all my secondary 1 Science students. It may also be beneficial for secondary 3 Physics students.
Please do not get the 3 types of transmission of heat mixed up. Heat is transmitted through 3 different ways: conduction, convection, radiation.
A quick recap: Conduction occurs in solids, liquids and gases, while convection occurs only in liquids and gases. Radiation requires no medium, which means it can even pass through vacuum! Please remember how each of these ways transmit heat. I will not elaborate them here so if you need help, read your notes and textbook, or look for me in school!
Now, when we say a thing is a good conductor, it means this thing can transmit heat efficiently (quickly) by conduction. Similarly, an insulator or bad conductor is a thing that is inefficient (slow) in transmitting heat by conduction. You may lose marks if you used the word "conductor" in a wrong context.
When we are describing a thing that is transmitting heat through radiation, we do not use the word "conductor". To describe things that are giving out heat through radiation, we use words like "emitter" or "radiator". And to describe things that are taking in heat through radiation, we use the word "absorber".
For example, let's look at the teapot, which has a silver shiny surface and is made of metal. It is a good conductor of heat because of it's material, metal. If you put hot tea in it, the whole teapot would quickly be hot to touch as its body is a good conductor of heat. However, it is also a bad emitter of heat because of its silver shiny surface, and this helps to keep the tea warm for a longer time. The silver shiny surface also makes it a bad absorber of heat, and thus it also keeps cool beverages cool for a longer time.
Please approach me for help if you still could not understand when to use "conductor", "insulator", "emitter" and "absorber" when describing the things that transmit heat.
Lastly, please bear in mind that there is no such thing as a "non-conductor of heat"! The statement "an insulator is not a conductor of heat" or "an insulator does not conduct heat" is WRONG! Do not be confused between insulators of heat and insulators of electricity. In the topic on electricity which will be covered in your secondary 2 syllabus, insulators do not conduct electricity. But in our current topic on transmission of heat, insulators of heat are bad conductors of heat. Everything can conduct heat, and an insulator is just a bad/poor conductor of heat. Insulators still conduct heat! As long as there is a difference in temperature, heat (or thermal energy) will flow from the region of higher temperature to the region of lower temperature. A good conductor allow the heat to flow faster while a poor conductor takes a much longer time for heat to be transmitted from the region of higher temperature to the region of lower temperature.
Please do not get the 3 types of transmission of heat mixed up. Heat is transmitted through 3 different ways: conduction, convection, radiation.
A quick recap: Conduction occurs in solids, liquids and gases, while convection occurs only in liquids and gases. Radiation requires no medium, which means it can even pass through vacuum! Please remember how each of these ways transmit heat. I will not elaborate them here so if you need help, read your notes and textbook, or look for me in school!
Now, when we say a thing is a good conductor, it means this thing can transmit heat efficiently (quickly) by conduction. Similarly, an insulator or bad conductor is a thing that is inefficient (slow) in transmitting heat by conduction. You may lose marks if you used the word "conductor" in a wrong context.
When we are describing a thing that is transmitting heat through radiation, we do not use the word "conductor". To describe things that are giving out heat through radiation, we use words like "emitter" or "radiator". And to describe things that are taking in heat through radiation, we use the word "absorber".
Please approach me for help if you still could not understand when to use "conductor", "insulator", "emitter" and "absorber" when describing the things that transmit heat.
Lastly, please bear in mind that there is no such thing as a "non-conductor of heat"! The statement "an insulator is not a conductor of heat" or "an insulator does not conduct heat" is WRONG! Do not be confused between insulators of heat and insulators of electricity. In the topic on electricity which will be covered in your secondary 2 syllabus, insulators do not conduct electricity. But in our current topic on transmission of heat, insulators of heat are bad conductors of heat. Everything can conduct heat, and an insulator is just a bad/poor conductor of heat. Insulators still conduct heat! As long as there is a difference in temperature, heat (or thermal energy) will flow from the region of higher temperature to the region of lower temperature. A good conductor allow the heat to flow faster while a poor conductor takes a much longer time for heat to be transmitted from the region of higher temperature to the region of lower temperature.
07 August 2010
Kinematics summary note
Summary note on distance-time graph and velocity-time graph for my sec 3 students; click for full size image. Pardon the untidy hand written note.
Happy long weekend and happy National Day on 9 August! (^_^)
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