Didn’t know ultrasound has such usage 😉
Tag Archives: things around us
Gravity Light – Amazing!
Physics around us
Heat Sink in PC
Heat sink plays a very important part in cooling of the Intel chip that powers the whole computer. Removal of thermal energy from the chip is vital. If the chip overheats, the ‘brain’ will be fried and it can’t function.
The features in the heat sink are there for a purpose. The metal portion is placed on top of the chip. Metal is used as metal is a good conductor of thermal energy. It helps to conduct thermal energy quickly away from the chip.
As the metal gets hot, it will radiate the thermal energy out. The design is such that it is fin-shaped, which increases the surface area, thus increases the rate in which rate of emission of infra-red radiation to the surrounding.
Theoretically, if this metal portion is coloured black will be better as black is a better absorber (from the chip) and emitter (emit out to surrounding) of infra-red radiation.
The fan creates a forced convection current to bring the hot air out and cool air in.
That’s the basic function of the heat sink found in most common PC.
Coronal Mass Ejection (CME)
The World in …
Straits Time article on 11 Dec 2012
Austrian Felix Baumgartner has become the first skydiver to go faster than the speed of sound, reaching a maximum velocity of 833.9mph (1,342km/h).
- Exit altitude: 128,100ft; 39,045m
- Total jump duration: 9’03”
- Freefall time: 4’20”
- Freefall distance 119,846ft; 36,529m
- Max velocity: 833.9mph; 1,342.8km/h; Mach 1.24
Its representative was the first to greet the skydiver on the ground. GPS data recorded on to a microcard in the Austrian’s chest pack will form the basis for the height and speed claims that are made.
These will be submitted formally through the Aerosport Club of Austria for certification.
There was concern early in the dive that Baumgartner was in trouble. He was supposed to get himself into a delta position – head down, arms swept back – as soon as possible after leaving his capsule. But the video showed him tumbling over and over.
Eventually, however, he was able to use his great experience, from more than 2,500 career dives, to correct his fall and get into a stable configuration.
Even before this drama, it was thought the mission might have to be called off. As he went through last-minute checks inside the capsule, it was found that a heater for his visor was not working. This meant the visor fogged up as he exhaled.
“This is very serious, Joe,” he told retired US Air Force Col Joe Kittinger, whose records he was attempting to break, and who was acting as his radio link in mission control at Roswell airport.
The team took a calculated risk to proceed after understanding why the problem existed.
Baumgartner’s efforts have finally toppled records that have stood for more than 50 years.
Kittinger set his marks for the highest, farthest, and longest freefall when he leapt from a helium envelope in 1960. His altitude was 102,800ft (31km). (His record for the longest freefall remains intact – he fell for more than four and a half minutes before deploying his chute; Baumgartner was in freefall for four minutes and 20 seconds).
Kittinger, now an octogenarian, has been an integral part of Baumgartner’s team, and has provided the Austrian with advice and encouragement whenever the younger man has doubted his ability to complete such a daring venture.
“Felix did a great job and it was a great honour to work with this brave guy,” the elder man said.
The 43-year-old adventurer – best known for leaping off skyscrapers – first discussed seriously the possibility of beating Kittinger’s records in 2005.
Since then, he has had to battle technical and budgetary challenges to make it happen.
What he was proposing was extremely dangerous, even for a man used to those skyscraper stunts.
At Sunday’s jump altitude, the air pressure is less than 2% of what it is at sea level, and it is impossible to breathe without an oxygen supply.
Others who have tried to break the records have lost their lives in the process.
Baumgartner’s team built him a special pressurised capsule to protect him on the way up, and for his descent he wore a next generation, full pressure suit made by the same company that prepares the flight suits of astronauts.
Although the jump had the appearance of another Baumgartner stunt, his team stressed its high scientific relevance.
The researchers on the Red Bull Stratos project say it has already provided invaluable data for the development of high-performance, high-altitude parachute systems, and that the lessons learned will inform the development of new ideas for emergency evacuation from vehicles, such as spacecraft, passing through the stratosphere.
Nasa and its spacecraft manufacturers have asked to be kept informed.
“Part of this programme was to show high-altitude egress, passing through Mach and a successful re-entry back [to subsonic speed], because our belief scientifically is that’s going to benefit future private space programmes or high-altitude pilots; and Felix proved that today,” said Art Thompson, the team principal.
In getting to 128,100ft, Baumgartner exceeded the altitude for the highest ever manned balloon flight achieved by Victor Prather and Malcolm Ross, who ascended to 113,720ft (35km) in 1961.
However, the FAI rules, state that to claim an official ballooning record, a balloonist must also bring the envelope down and therefore the Austrian’s altitude will forever remain just an unofficial mark.
Free-fall + breaking sound barrier
Examples of a hydraulic system
Static Electricity: Playground slide
Due to charging by friction as Levonne slides down the slide, assuming there is a transfer of electrons from slide to her body, her body will be negatively charged.
Each strand of her hair is negatively charged too, hence they stand and repel each other.
Harmful effect of ultraviolet
Ultraviolet is part of the electromagnetic spectrum. One of its application is artificial sun tanning in sunbeds.
But beware of the harmful effect of skin cancer. Read the articles below.
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Next Generation Broadband Network (NGNBN)
Optical fibre network technology allows us to surf net approximately 100 times faster than our current Internet connections.
Optical fiber cables are thin strands of glass, about the thickness of a human hair, that permit the transmission of data using light over longer distances and at higher connection speed of 1Gbps and above. The blue and red cables in the photo are the optical fibre cables.
The transmission of light through the optical fibre cable uses physics concept of Total Internal Reflection (TIR).
For TIR to occur,
1) light must be traveling from a denser to less dense medium.
2) incidence angle is greater than critical angle.
Balancing Toys
Balancing toys always return to its original position as their centre of gravity (CG) are below the pivot (balancing) point. This kind of system will create a restoring moment which helps to return the system to its original position when displaced slightly.
Such systems are in stable equilibrium. Characteristic of such system is that when displaced, the CG rises.
3E1 2011 Project Gp5: Various Physics Experiments
Another great video by:
Terri, Coryn, Yahui, Desiree, Sherilyn and Ziao Cinch
You gals are funny haha…enjoyed the video.
3E1 2011 Project Gp 1 – Moments
Hi 3E1,
This is the first video project submitted by Bernice Goh, Tang Yun Hui, Rachel Lee, Kho Yun Suen, Jezebel Tay! Great job!
I like the video! It’s professionally done up =)
Comment of the video and answer their question!
Boiling water at 60 °C in lab!
Water boils at 100°C. In the view below, the water is initially at around 60°C.
How is this possible?
Explanation:
At sea level, where the pressure is atmospheric pressure (approx 105 000 Pa), the boiling point of water is 100°C.
In the video as air is sucked from the sealed container, the pressure in the container decreases. This lowers the boiling point of the water to around 60°C, hence water will boil and bubbles are formed.
It is similar to boiling water at high altitude, like on top of Mount Everest (about 8 km high). Water will boil around 70°C to to lower atmospheric pressure at high altitude.
Physics of Construction Lifting Truck
1) Why are the 4 extended legs necessary?
This is to increase the area of base of the truck to increase the stability. From our theory, as long as the weight acting vertically downward from the centre of gravity is within the area of base, there will be a restoring moment to bring the truck back to its original position, hence increases its stability.
2) In what situation will the truck topple? (note the the centre of gravity (CG) of the truck is in general very low due to mass concentration at the base)
Basically, there are 2 situdation:
– if the load that is lifted is too heavy, the overall new CG of the truck and load might shift outside the area of base, hence causing the truck to topple. i.e. the clockwise moment created by the load is created than the anticlockwise moment created the weight of truck.
– If the angle of tilt is too much which increases the perpendicular distance from load to pivot. Likewise, the overall CG might be outside the area of base and there is a net clockwise moment.
3) What is the purpose of the metal plate underneath the legs?
The purpose is to increase the area of base. The whole weight of the truck is spread over the 4 legs. Since P = F/A, with a bigger base area, the pressure acting on the ground will be reduced. This is to minimise any damages done to the ground.
Innovative guy using light concepts to brighten one’s life
Thank you Yue Jie (5N1 2011) for sharing!
Explanation
Sent from my iPad
Innovative guy using light concepts to brighten one’s life
Thank you Yue Jie (5N1 2011) for sharing!
Explanation
Sent from my iPad
Concave mirror
These photos are taken in Sentosa Resort World – Festive Hotel.
In some hotels, they have cosmetic mirror like the one you see in the photos. There are 2 sides of the mirror which you can use. Law of reflections are obeyed on both mirrors.
On one side, it is a normal plane mirror. Your 5 characteristic of mirror image apply here.
On the other side, it is a concave mirror, which creates a magnified image for you to see the ‘flaws’ on your face =)
Double-glazed windows and doors in hotel
These photos are taken at Sentosa Resort World – Festive Hotel.
Most hotels have double-glazed windows and doors.
From thermal physics, we have learned that it has a layer of air in between 2 layers of glass. Air is a poor conductor, hence thermal energy from outside the hotel room entering the room will be reduced. In this way, the room can be kept cool, and hotel expenditure on air-conditioning can be reduced.
On the other hand, due to this feature, it helps to sound proof the room too. With double-glazed windows and a layer of air, external sound from outside the room will be softened due to these additional layers. Hence you are able to have a good sleep in the room!
Spraying of mist in air – what’s the purpose?
This structure is located at Marina Bay, beside the Marina Bay Sands. It sprays out mist into the air. What is the main purpose of this in terms of thermal physics?
<p>Spray out mist. What’s the function? from evantoh on Vimeo.</p>
You might have come across similar features like this in other places like coffee shop, al fresco Starbucks etc.
Explanation:
Mist contains tiny droplets of water. When it is sprayed out to the surrounding, it will evaporate very fast.
The higher rate of evaporation is due to the tiny droplets of water having a relatively higher expose surface area compared to a body of water of the same mass.
As the droplets of water evaporate, thermal energy is taken from the surrounding air to change the water to a gaseous state. Hence temperature of the surrounding air drops, giving the cooler and conducive environment in a hot tropical weather in Singapore.
Restoring moment
This Lego structure which Daniel and Danry made is ‘Stable equilibrium’
Characteristics of stable equilibrium:
– when displaced, centre of gravity (cg) rises.
– the weight of the basket will create a restoring moment which returns the basket to its original position.
– when at rest, the weight of CG is directly below the pivot.
Below is a brief explanation
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An example of Total Internal Reflection
Some designer lightings like that one show in the video make use of total internal reflection. This was taken at Spring Maternity @NEX Jul 2011.
An Example of Total Internal Reflection from evantoh on Vimeo.
Each strand is actually make of transparent plastic-like material, which is flexible and has higher optical density than the air.
Recall the 2 conditions for total internal reflection to take place
1: light is traveling from denser medium (plastic) to the less dense medium (air)
2: angle of incidence is greater than critical angle
Hence from the centre light source, light can total internal reflection and comes out from the other end of each strand. There you have it! A unique designer lighting, just making use of physics!
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Evan's Space 