Archive for the ‘2009-10 G9 Int Sci’ Category

Waves on the Earth

Thursday, March 25th, 2010
Tsunami Hazard Zone by hey mr glen on flickr

Tsunami Hazard Zone by hey mr glen on flickr

These are some of the questions we should be able to answer after some research.  Check out these videos that explain a bit about earthquakes.  This one relates sound waves to earthquakes.  This one relates transverse and longitudinal waves to earthquakes. 

  • How are water waves formed?
  • Why are earthquakes so damaging?
  • How are tsunamis created?
  • Why do some indigenous tribes place their ears to the ground to hear if someone is approaching?

Waves questions

Wednesday, March 17th, 2010

The distance between repeating parts of the pattern (the length of each single wave) is known as the wavelength (l).  Wavelengths can be measured from anywhere to the next identical part of the wave.

Frequency is a measure of how often something happens in one second. The symbol of frequency is f and the units are hertz (Hz). The relationship between velocity, frequency and wavelength is:

 Velocity (m/s) = frequency (Hz) x wavelength (m)

Light waves travel much faster than sound waves. The speed of a set of waves can be found by using information about the distance travelled and time taken or from information about the frequency and wavelength.

Distance, speed and time are connected by:

Speed (m/s)   =   Distance (m) / time (s)

Example An echo takes 1.5 s to reflect from the front wall of a school building 250m away. What is the speed of sound in air?

Distance for echo = 2 x 250 m = 500 m                                Time taken   = 1.5 s

Speed = distance/time = 500/1.5 = 333m/s

This method is practical at school only for the measurement of the speed of sound.

Example Capital Radio broadcasts throughout the London area using radio waves of frequency 1548kHz, travelling at 300000km/s. To what wavelength would you tune a radio to receive Capital programmes?

Speed   = 300000km/s = 300000000m/s                  Frequency = 1548 kHz (1 548 000 Hz)

Wavelength = speed/frequency  = 300 000 000/1 548 000 = 194 m 

Using your knowledge of the wave equation, and the relationship between frequency and time [f = 1/T], answer the following questions:-

  1. If the waves in the ocean are timed so that they come to shore every 1.74 seconds, what is the frequency of these waves? (Show your working and don’t forget units).
  2. A radio wave has a frequency of 2 MHz (2 MegaHertz = 2 000 000 Hz). Calculate the time period between successive waves.
  3. A radio station broadcasts with a wavelength of 160m. If the velocity of the radio signal is 3 x 108 m/s, calculate the frequency of the wave. 
  4. If all the 1.2 billion people in China jump up and down at the same time, they will create a shock wave that will travel around the Earth in all directions.  This wave will focus and peak on the other side of the Earth, exactly opposite China (around California).  If the circumference of the Earth is 40 000km and the speed of sound on the Earth’s surface is 2850m/s, calculate how long it will take for California to crumble into the sea due to the shock wave.

Grade 9 Integrated Science 1 docwaves practice questions mark scheme

What are waves?

Tuesday, March 16th, 2010
green sine by bdu on flickr

green sine by bdu on flickr

New topic – yay!  We’ll learn about waves.  Here are some of the points we’ll try and answer:-

  • What is a wave?
  • What is the difference between transverse and longitudinal waves?
  • What are some examples of transverse and longitudinal waves?
  • What are the amplitude, frequency and wavelength of a wave?

Anatomy of Waves

We’ll then take a look at the wave equation       v = f λ

This shows us the relationship between speed of a wave v, the time it takes for a particle to vibrate up and down, and the distance between successive waves λ.  You’ll need your calculators as we practice solving problems in class.

Which energy source is best for the Philippines?

Wednesday, February 24th, 2010
Coal transport by MoToMo on flickr

Coal transport by MoToMo on flickr

For our culminating activity in this unit we will be getting you into groups and asking you to research, present and debate on which is the best source of energy for the Philippines.  Look at this handout for full details of the work, including the rubric for assessment.  Amended Energy Topic Performance Task

Each group of 4 students will be given one source of energy.  Each person on the group will take on a different role – either that of engineer, economist, environmentalist, or a  member of the public – and put together a convincing argument as to why their particular source of energy should be used.  You will also need to have some knowledge of other sources of energy in order to be able to counter any arguments against your source. 

Solar Panels by clownfish on flickr

Solar Panels by clownfish on flickr

You will be given 2 full lessons to research this.  The next lesson we will listen to each presentation, make some notes on this sheet: ENERGY PERFORMANCE TASK Presentation Notes and then vote on which energy source we think should be used.

This should be fun!

Peak oil

Tuesday, February 23rd, 2010
Current world oil reserves by ChartsBin on flickr

Current world oil reserves by ChartsBin on flickr

In class today we discussed the idea of exponential growth and watched this video by Chris Martenson.  We discussed the idea of peak oil, and how this was different to “oil running out” by watching this video.  We then researched which countries have oil reserves, and how much, and discovered that according to CIA world factbook, that the Philippines is #62 on the list.

We will discuss the following essential questions:

  • Why have humans become so much more productive over the last 250 years when compared to the previous 250,000?
  • What is peak oil, and should we be worried that some people say we have reached it?
  • What will be the consequence of an ever increasing human population and falling fossil fuel energy reserves?
  • Will developing countries ever realize the standard of living enjoyed by people in developed countries?

Sharkwater follow up

Friday, February 19th, 2010
Sharkwater poster by thegreenpages on flickr

Sharkwater by thegreenpages on flickr

After watching SHARKWATER in class, where we discussed many of the issues surrounding food webs and man’s impact on them, particularly in the ocean, I found this article in the news today, so thought I’d share it with you.

Creativity with Carbon

Friday, February 19th, 2010

Imagine you are a carbon atom in a molecule of carbon dioxide in the air.  Close your eyes.  Really imagine yourself as that carbon atom.  Your task is to describe the journey you take from being part of carbon dioxide in the air, through the carbon cycle, until you return to the air again.  Here is my attempt at the beginnings of such a story to give you the idea.  You do not need to start in this way.  You decide.  Get creative!  Let your imagination work!

There I was, happily floating around in my usual gaseous form along with several of my brothers and sisters  (other carbon dioxide molecules), and my good friends nitrogen and oxygen.  We were having a great time bumping into one another, when I got dangerously close to a leaf.  Everyone had always told me to stay away from green plants, that I could get sucked into a stoma and never be seen again.  Before I realized what was happening, I was inside a chloroplast and going through a very fast reaction where I had to let go of my two oxygen atoms, and for a moment be entirely alone.  Before long, I found some other carbons and we joined together, 6 of us, 12 hydrogen friends and 6 oxygen buddies to form a glucose molecule….

Carbon cycle

Thursday, February 11th, 2010
Nature by jaxxon on flickr

Nature by jaxxon on flickr

We’re going to try and connect all that we have been learning – respiration, combustion, photosynthesis, food chains – into one big carbon cycle. This brainpop video will help get you started.  

This one on fossil fuels explains where oil, coal and gas come from, and leads into our next section on the importance of oil and how to separate it out by distillation.  This video explains how this works in an oil refinery. We’ll do a world energy audit and look at where the natural resources are and what the alternative energy sources might be.

Food chains and food webs

Thursday, February 4th, 2010
fox chasing rabbit 0121 by pixpoils on flickr

fox chasing rabbit 0121 by pixpoils on flickr

What is a food chain?  It is a representation of energy flow through an ecosystem.  All food chains begin with a green plant, that traps energy from the Sun. We’ll look at lots of examples, and get to grips with terms such as producer, consumer, carnivore, herbivore, autotroph, heterotroph. 

Food chains have limited use in looking at the big picture in an ecosystem, since there is usually more than one organism feeding on each food source.  For a more realistic view of what happens in nature we need to consider food webs.  A food web is a number of inter-connected food chains.

Check out this brainpop video.

We’ll discuss the idea of interdependence between all the organisms within a food chain, and look at how disease or a change in the environment affects things.

We need to answer this important question:  why are food chains short (only 3 or 4 organisms long)?

We’ll use explorelearning to help us with these concepts.  Log in using the details given in class, type a search for food chains.  Follow the instructions for the food chain, praire ecosystem and forest ecosystem activities.  Enjoy!

And here are a couple more sites to help reinforce these ideas.  This one is from bbc science and this one allows you to explore a number of food webs.

This booklet by Mr Boulton might be useful for review and notes.Booklet to learn about ecology

Greenhouses and photosynthesis

Thursday, January 28th, 2010

Take a look at this sheet (thanks Mr Boulton).  Greenhouse Assessment Task

It gives some background info on how greenhouses work, and finishes with some questions about the links with photosynthesis and respiration.