Sunday, March 29, 2009
Tallest buildings !
What are the tallest buildings in Singapore ?
In Singapore, three buildings share the title for the tallest building in the country, namely, UOB Plaza One, Republic Plaza and OUB Centre.
OUB centre
Address : 1 Raffles Place.
Height :280 m (919 ft)
Floors : 63
Built in : 1986
UOB Plaza One
Address : 80 Raffles Place
Height: 280 m (919 ft)
Floors : 66
Built in : 1992
Republic Plaza
Address: 9 Raffles Place
Height: 280 m (919 ft)
Floors : 66
Built in: 1995
Tallest buildings in the world
1. Burj Dubai(Not completed)
Place : Dubai , United Arab Emirates
Height : 818 m 2,684 ft
Floors :162
Expected to be completed by September 2009
2. Taipei 101
Place : Taipei , Taiwan
Height: 509 m 1,671 ft Floors : 101
Built in : 2004
3.Shanghai World Financial Center
Place : Shanghai , China
Height: 492 m 1,614 ft
Floors : 101
Built in : 2008
Currently in the world , the tallest building is Taipei 101 but soon , the tallest building will be Burj Dubai after it is build.
Reference taken from : Wikipedia .
What are the tallest buildings in Singapore ?
In Singapore, three buildings share the title for the tallest building in the country, namely, UOB Plaza One, Republic Plaza and OUB Centre.
OUB centre
Address : 1 Raffles Place.
Height :280 m (919 ft)
Floors : 63
Built in : 1986
UOB Plaza One
Address : 80 Raffles Place
Height: 280 m (919 ft)
Floors : 66
Built in : 1992
Republic Plaza
Address: 9 Raffles Place
Height: 280 m (919 ft)
Floors : 66
Built in: 1995
Tallest buildings in the world
1. Burj Dubai(Not completed)
Place : Dubai , United Arab Emirates
Height : 818 m 2,684 ft
Floors :162
Expected to be completed by September 2009
2. Taipei 101
Place : Taipei , Taiwan
Height: 509 m 1,671 ft Floors : 101
Built in : 2004
3.Shanghai World Financial Center
Place : Shanghai , China
Height: 492 m 1,614 ft
Floors : 101
Built in : 2008
Currently in the world , the tallest building is Taipei 101 but soon , the tallest building will be Burj Dubai after it is build.
Reference taken from : Wikipedia .
what we could have been, 4:52 AM.
Saturday, March 28, 2009
Why don't penguins and polar bears live together ?
I search the internet and found a few answers , they are quite similar though:
1. Polar bears and Penguins do not live in the same place. Polar Bears can be found in the Arctic, in the northern hemisphere, whereas all seventeen species of penguin are found in the the southern hemisphere. They can not live together as each one is adapted to survive in its own climate and habitat and those habitats can be as far apart as the ends of the world.
2. The main reason why you will never see penguins and polar bears in the same region together is beacause the polar bear lives up near the North Pole. They are in the cold areas that are on top of the world. On the other hand, the penguin (such as the emperor penguins) live in the Anartic areas (or south poles) that are at the bottom of the world. Both the polar bears and penguins live and dwell in areas that are extremely cold with a lot of snow and ice. However, the polar bear lives in the northen artic regions and the penguins lives in the southern artic regions. The only time that you may see penguins and polar bears living in the same areas is in a zoo. Otherwise, one lives on top of the world and the other lives on the bottom of the world.
Taken from : http://wiki.answers.com/Q/Why_don%27t_penguins_and_Polar_bears_live_together and http://answers.yahoo.com/question/index?qid=20071116201706AAuYNNX
I search the internet and found a few answers , they are quite similar though:
1. Polar bears and Penguins do not live in the same place. Polar Bears can be found in the Arctic, in the northern hemisphere, whereas all seventeen species of penguin are found in the the southern hemisphere. They can not live together as each one is adapted to survive in its own climate and habitat and those habitats can be as far apart as the ends of the world.
2. The main reason why you will never see penguins and polar bears in the same region together is beacause the polar bear lives up near the North Pole. They are in the cold areas that are on top of the world. On the other hand, the penguin (such as the emperor penguins) live in the Anartic areas (or south poles) that are at the bottom of the world. Both the polar bears and penguins live and dwell in areas that are extremely cold with a lot of snow and ice. However, the polar bear lives in the northen artic regions and the penguins lives in the southern artic regions. The only time that you may see penguins and polar bears living in the same areas is in a zoo. Otherwise, one lives on top of the world and the other lives on the bottom of the world.
Taken from : http://wiki.answers.com/Q/Why_don%27t_penguins_and_Polar_bears_live_together and http://answers.yahoo.com/question/index?qid=20071116201706AAuYNNX
what we could have been, 4:46 AM.
Thursday, March 26, 2009
Heat
In physics and thermodynamics, heat (symbolized by Q) is any transfer of energy from one body or system to another due to a difference in temperature. Heat can be transferred between objects by radiation, conduction and convection.
Radiation
Radiation heat transfer is concerned with the exchange of thermal radiation energy between two or more bodies. Thermal radiation is defined as electromagnetic radiation in the wavelength range of 0.1 to 100 microns (which encompasses the visible light regime), and arises as a result of a temperature difference between 2 bodies. No medium need exist between the two bodies for heat transfer to take place (as is needed by conduction and convection). Rather, the intermediaries are photons which travel at the speed of light. The heat transferred into or out of an object by thermal radiation is a function of several components. These include its surface reflectivity, emissivity, surface area, temperature, and geometric orientation with respect to other thermally participating objects. In turn, an object's surface reflectivity and emissivity is a function of its surface conditions (roughness, finish, etc.) and composition.
Conduction
Conduction is heat transfer by means of molecular agitation within a material without any motion of the material as a whole. If one end of a metal rod is at a higher temperature, then energy will be transferred down the rod toward the colder end because the higher speed particles will collide with the slower ones with a net transfer of energy to the slower ones.
Convection
Convection is heat transfer by mass motion of a fluid such as air or water when the heated fluid is caused to move away from the source of heat, carrying energy with it. Convection above a hot surface occurs because hot air expands, becomes less dense, and rises. Hot water is likewise less dense than cold water and rises, causing convection currents which transport energy. Convection can also lead to circulation in a liquid, as in the heating of a pot of water over a flame. Heated water expands and becomes more buoyant. Cooler, more dense water near the surface descends and patterns of circulation can be formed, though they will not be as regular
Reference taken from : http://hyperphysics.phy-astr.gsu.edu/Hbase/thermo/heatra.html and http://www.efunda.com/formulae/heat_transfer/radiation/overview_rad.cfm
what we could have been, 4:29 AM.
Density of Ice VS water
Ans: Water . When ice is put into water , the ice floats, but when the ice slowly melts, it turns into water as well.
Density Comparison to Water: In chemistry, the density of many substances is compared to the density of water. Does ice float on water or sink in the water? Everyone knows what happens in the case of ice cubes in a glass of water. Look at the graphic on the top.
Why does ice float?
What other observations or facts are known?
- Because ice floats, we can infer that ice must be less dense than water.
- If water is frozen in a glass jar, the glass jar breaks.
- If a pop can freezes, it will also burst.
- From both of the above we infer that the volume of the ice has increased.
Conclusion: The volume of ice must be greater than the same mass of liquid water. Why does the volume increase?
So which is denser ? Ice or water ?Ans: Water . When ice is put into water , the ice floats, but when the ice slowly melts, it turns into water as well.
what we could have been, 4:10 AM.
Dynamic Equilibrium
When two opposing rates of change are equal—such as the rate of evaporation
and the rate of condensation in our closed system—we say the system has reached
a dynamic equilibrium. Dynamic equilibrium is found in many of the systems that
you will encounter in chemistry, so it is important to have a general understanding
of the conditions necessary to create it. First, the system must exhibit two ongoing,
opposing changes, from state A to state B and from state B to state A. For example,
state A is the liquid, state B is the vapor, and the two opposing changes are evaporation
and condensation. For a dynamic equilibrium to exist, the rates of the two opposing
changes must be equal, so that there are constant changes between state A and state
B but no net change in the components of the system. In the dynamic equilibrium of
our liquid-vapor system, the liquid is constantly changing to vapor, and the vapor is
constantly changing to liquid, but no net change in the amounts of liquid and vapor
is observed .
When two opposing rates of change are equal—such as the rate of evaporation
and the rate of condensation in our closed system—we say the system has reached
a dynamic equilibrium. Dynamic equilibrium is found in many of the systems that
you will encounter in chemistry, so it is important to have a general understanding
of the conditions necessary to create it. First, the system must exhibit two ongoing,
opposing changes, from state A to state B and from state B to state A. For example,
state A is the liquid, state B is the vapor, and the two opposing changes are evaporation
and condensation. For a dynamic equilibrium to exist, the rates of the two opposing
changes must be equal, so that there are constant changes between state A and state
B but no net change in the components of the system. In the dynamic equilibrium of
our liquid-vapor system, the liquid is constantly changing to vapor, and the vapor is
constantly changing to liquid, but no net change in the amounts of liquid and vapor
is observed .
what we could have been, 3:35 AM.
Thermal Equilibrium
It is observed that a higher temperature object which is in contact with a lower temperature object will transfer heat to the lower temperature object. The objects will approach the same temperature, and in the absence of loss to other objects, they will then maintain a constant temperature. They are then said to be in thermal equilibrium. Thermal equilibrium is the subject of the Zeroth Law of Thermodynamics.
Taken from : http://hyperphysics.phy-astr.gsu.edu/Hbase/thermo/thereq.html
what we could have been, 3:28 AM.
Sunday, March 1, 2009
Thermal physics is a field of science that deals with heat and temperature. When we study topics like global warming, the Earth's solid and liquid cores, and the way in which energy flows from the center of the Sun to its surface, we need to understand thermal physics.
Temperature is a familiar idea that is a big part of thermal physics. Three scales for measuring temperature are in common use: Fahrenheit, Celsius (or Centigrade), and Kelvin. The temperature of a gas is really a measure of the average speed with which molecules or atoms are hurtling about. We infer the temperatures of stars from their colors; hot stars are blue while cooler ones are red.
In our everyday speech, heat and temperature mean the same thing. In the language of thermal physics, the two terms have different meanings. Heat is the amount of thermal energy stored in an object. Heat can flow from one object to another, transferring energy in the process. The flow of heat can melt ice or warm the surfaces of planets near a star. The Laws of Thermodynamics describe the fundamental physics of heat and its flows.
Heat flows from hot places to cold ones, and often drives the motions of other materials. Convection and conduction are two common ways by which heat can flow. Electromagnetic radiation, especially at infrared wavelengths, can convey heat across a vacuum. We study heat flows to understand the circulation of ocean currents, the outflow of energy from the Sun, and the workings of rocket motors.
There are two types of thermodynamic instruments, the meter and the reservoir. A thermodynamic meter is any device which measures any parameter of a thermodynamic system. In some cases, the thermodynamic parameter is actually defined in terms of an idealized measuring instrument. For example, the zeroth law states that if two bodies are in thermal equilibrium with a third body, they are also in thermal equilibrium with each other. This principle, as noted by James Maxwell in 1872, asserts that it is possible to measure temperature. An idealized thermometer is a sample of an ideal gas at constant pressure. From the ideal gas law PV=nRT, the volume of such a sample can be used as an indicator of temperature; in this manner it defines temperature. Although pressure is defined mechanically, a pressure-measuring device, called a barometer may also be constructed from a sample of an ideal gas held at a constant temperature. A calorimeter is a device which is used to measure and define the internal energy of a system.
Reference taken from : http://www.windows.ucar.edu/tour/link=/physical_science/physics/thermal/sw_thermal.html and http://en.wikipedia.org/wiki/Thermal_physics
Reference taken from : http://www.windows.ucar.edu/tour/link=/physical_science/physics/thermal/sw_thermal.html and http://en.wikipedia.org/wiki/Thermal_physics
what we could have been, 9:48 PM.
The Golden Gate Bridge is a suspension bridge spanning the Golden Gate, the opening of the San Francisco Bay onto the Pacific Ocean. As part of both U.S. Route 101 and State Route 1, it connects the city of San Francisco on the northern tip of the San Francisco Peninsula to Marin County. The Golden Gate Bridge was the longest suspension bridge span in the world when it was completed in 1937, and has become an internationally recognized symbol of San Francisco and California. Since its completion, the span length has been surpassed by eight other bridges. It still has the second longest suspension bridge main span in the United States, after the Verrazano-Narrows Bridge in New York City. In 2007, it was ranked fifth on the List of America's Favorite Architecture by the American Institute of Architects.
Reference taken from : http://en.wikipedia.org/wiki/Golden_Gate_Bridge
what we could have been, 3:14 AM.
*Click to view .The Tacoma Narrows Bridge is a pair of mile-long suspension bridges in the U.S. state of Washington, which carry State Route 16 across the Tacoma Narrows between Tacoma and the Kitsap Peninsula. They replaced a bridge that was opened to traffic on n July 1, 1940 and which became famous four months later for a dramatic wind-induced structural collapse that was caught on motion picture film. The original span's motion earned it the nickname "Galloping Gertie". Due to materials shortages as a result of World War II, it took 10 years to build a replacement bridge, which opened October 14, 1950. The 1950 replacement bridge was sometimes referred to as "Sturdy Gertie", and, like its predecessor, was the third longest suspension span in the world at the time of its construction. Population growth on the Kitsap peninsula caused the bridge to exceed its vehicle capacity, and a parallel bridge was constructed to carry eastbound traffic, while the 1950 bridge was reconfigured to carry westbound traffic. The new bridge opened July 15, 2007, making the Tacoma Narrows Bridge the longest twin suspension span in the world.
This video shows how Tacoma Narrow Bridge Collapsed .
Reference taken from : http://en.wikipedia.org/wiki/Tacoma_Narrows_Bridge
what we could have been, 3:03 AM.
Where is the center of gravity of the pendulum bob ?
In the picture , is just a pendulum itself , the center of gravity is in the middle of the pendulum as you can see , in my drawing , it is not exactly accurate .
In this second picture , it is a pendulum with plasticine on top , the position of the center of gravity would be higher .
In this third picture , the plasticine is completely wrapped around the pendulum (take that the plasticine is wrapped and covered equally) , the center of gravity would be in the center like the first picture .
In this last picture , there's a hole in the middle , the center of gravity ... I'm guessing that it would still be in the middle .
In the picture , is just a pendulum itself , the center of gravity is in the middle of the pendulum as you can see , in my drawing , it is not exactly accurate .
In this second picture , it is a pendulum with plasticine on top , the position of the center of gravity would be higher .
In this third picture , the plasticine is completely wrapped around the pendulum (take that the plasticine is wrapped and covered equally) , the center of gravity would be in the center like the first picture .
In this last picture , there's a hole in the middle , the center of gravity ... I'm guessing that it would still be in the middle .
In class , Mr Lim asked us to find out where's the center of the gravity on each of the pendulum respectively . All 3 'pendulums' were done by yours truly :D Despite my ugly and not exactly very accurate drawings i hope you can get an idea of what this is about , even if they look like eggs ;P .
Do leave a comment if i made a mistake .
Do leave a comment if i made a mistake .
what we could have been, 2:36 AM.
What is center of gravity ?
The center of gravity of a collection of masses is the point where all the weight of the object can be considered to be concentrated. In physics, the center of gravity of an object is the average location of its weight in a particular environment (and relative to a particular reference point). In a (hypothetical) uniform gravitational field, it coincides with the object's center of gravity. For this reason (i.e. that in everyday experience the Earth's gravitational field may be considered uniform) the center of gravity (CG) of an object is a point at which the object's mass can be assumed, for many purposes, to be concentrated.
Center of mass
In physics, the center of mass of a system of particles is a specific point at which, for many purposes, the system's mass behaves as if it were concentrated. The center of mass is a function only of the positions and masses of the particles that comprise the system. In the case of a rigid body, the position of its center of mass is fixed in relation to the object (but not necessarily in contact with it). In the case of a loose distribution of masses in free space, such as shot from a shotgun, the position of the center of mass is a point in space among them that may not correspond to the position of any individual mass.
Difference between center of gravity and center of mass
Unlike the center of mass, the center of gravity of an object can vary, depending on the objects environment. Note that the center of gravity of a body is not a point such that the gravitational field due to that body is equal to the gravitational field if all mass were concentrated there. Such a point usually does not exist. For example for two equal spherical bodies the center of gravity of the system is forced by symmetry, and lies midway between the centers; but gravity due to the system is not very large near that point.
Videos ! :
Reference taken from : http://www.nationmaster.com/encyclopedia/Center-of-gravity and http://www.nationmaster.com/encyclopedia/Center-of-mass
The center of gravity of a collection of masses is the point where all the weight of the object can be considered to be concentrated. In physics, the center of gravity of an object is the average location of its weight in a particular environment (and relative to a particular reference point). In a (hypothetical) uniform gravitational field, it coincides with the object's center of gravity. For this reason (i.e. that in everyday experience the Earth's gravitational field may be considered uniform) the center of gravity (CG) of an object is a point at which the object's mass can be assumed, for many purposes, to be concentrated.
Center of mass
In physics, the center of mass of a system of particles is a specific point at which, for many purposes, the system's mass behaves as if it were concentrated. The center of mass is a function only of the positions and masses of the particles that comprise the system. In the case of a rigid body, the position of its center of mass is fixed in relation to the object (but not necessarily in contact with it). In the case of a loose distribution of masses in free space, such as shot from a shotgun, the position of the center of mass is a point in space among them that may not correspond to the position of any individual mass.
Difference between center of gravity and center of mass
Unlike the center of mass, the center of gravity of an object can vary, depending on the objects environment. Note that the center of gravity of a body is not a point such that the gravitational field due to that body is equal to the gravitational field if all mass were concentrated there. Such a point usually does not exist. For example for two equal spherical bodies the center of gravity of the system is forced by symmetry, and lies midway between the centers; but gravity due to the system is not very large near that point.
Videos ! :
Reference taken from : http://www.nationmaster.com/encyclopedia/Center-of-gravity and http://www.nationmaster.com/encyclopedia/Center-of-mass
what we could have been, 1:42 AM.
