Date of publication: 2017-07-08 20:48
Radial and Harp cable-stayed bridges
I saw this interesting structures EEI at a Panel Meeting. It was undertaken by students at Redlands College, near Brisbane. My thanks to student Josh for use of his diagrams and to physics teacher Dan Graham for providing the details.
There are many problems with this though. Firstly, you may wish to know if the sausage is an ohmic resistor - by increasing V across its ends and noting the current through it. But herein lies the problem: as you increase V the sausage will warm up due to Joule heating and its resistance will thus change. You have to keep temperature constant for Ohm's Law to be checked. That's your first problem.
Roof colours - white vs black
Nobel laureate Steven Chu, former professor of physics at the University of California and . Energy Secretary in President Obama's administration says white paint is what's needed to fix global warming. However, Steven Chu said, even if we paint every roof white, there was no silver bullet for tackling climate change, and said a range of measures should be introduced, including painting flat roofs white. Making roads and roofs a paler color could have the equivalent effect of taking every car in the world off the road for 66 years. That sounds like an ideal EEI.
As the torch is moved down the side of the beaker the beam of light appears more yellow as it has to travel through more and more of the cloudy liquid to reach your eye. He suggested photographing the view from above (see photos) and analysing the image for RGB levels. Stephen suggested using the photo analysis program Imagej but I found some of the other on-line apps easier to use. For the data below I just used Martin Krzywinski's Image Color Summarizer - /color_summarizer/. The colour doesn't appear much different to the human eye but a difference there is.
The attenuation (energy losses) of sound in air is due to several factors including viscous, thermal and rotational losses (&prop f 7 ) and vibrational relaxation of gas molecules. The attenuation of sound depends on temperature, water-vapour content and frequency.
We continue to listen to and involve teachers every step of the way to help us develop new physics specifications that will inspire and motivate your students and lay the foundations for further study in physics or engineering.
Measuring bounce and splash heights is another thing. Dave suggested we use a tray of water 5 cm deep and a sheet of black cardboard with a ruler attached. The splash height was obvious from the droplets on the black cardboard. To see the bounce heights he videoed the with an ordinary camera and scrolled through the frames to see the bounce height ( VLC Player works okay for this). This is not necessary if you are just doing splash heights. You can see Dave's video here. This EEI would be so much fun.
Thermal Conductivity - Å ngströ m's method revisited
The conductivity of heat through a substance is a significant problem that affects many areas of material science and engineering. How to measure the rate of heat conduction is a big issue. It applies to the design of solar panels, drawing heat from electrical components and even materials used in dentistry. Sometimes they mount semiconductors on diamonds to prevent damage from overheating, since diamonds have an extremely high thermal conductivity.
A good EEI would be to have the setup shown below and then use trial and error (adding or subtracting masses from the hanging bucket) to get the block to slide at constant speed. Using a datalogger would do this fine. Then load up the sliding mass and add more masses to the bucket to get constant speed each time.