Some people have created temperatures very close to absolute zero: the record temperature was 100 pK (one hundred picokelvin, equal to 10 kelvin) above absolute zero. Even getting close to absolute zero is difficult because anything that touches an object being cooled near absolute zero would give heat to the objects. Scientists use lasers to slow atoms when cooling objects to very low temperatures.
The kelvin and Rankine temperature scales are defined so that absolute zero is 0 kelvin (K) or 0 degrees Rankine (°R). The Celsius and Fahrenheit scales are defined so that absolute zero is −273.15 °C or −459.67 °F.
At this stage the pressure of the particles is zero. If we plot a graph to it, we can see that the temperature of the particles is zero. The temperature cannot go down any further. Also, the particles cannot move in "reverse" either because as the movement of particles is vibration, vibrating in reverse would be nothing but simply vibrating again. The closer the temperature of an object gets to absolute zero, the less resistive the material is to electricity therefore it will conduct electricity almost perfectly, with no measurable resistance.
The Third Law of Thermodynamics says that nothing can ever have a temperature of absolute zero.
The Second Law of Thermodynamics says that all engines that are powered by heat (like car engines and steam train engines) must release waste heat and can not be 100% efficient. This is because the efficiency (percent of energy the engine uses up that is actually used to do the engine's job) is 100%×(1-T/T), which only is 100% if the outside temperature is absolute zero which it cannot be. So, an engine cannot be 100% efficient, but you can make its efficiency closer to 100% by making the inside temperature hotter and/or the outside temperature colder.
Cylinder
A cylinder is one of the most basic curved three dimensional geometric shapes, with the surface formed by the points at a fixed distance from a given line segment, known as the axis of the cylinder. The shape can be thought of as a circular prism. Both the surface and the solid shape created inside can be called a "cylinder". The surface area and the volume of a cylinder have been known since ancient times.
In differential geometry, a cylinder is defined more broadly as a ruled surface which is spanned by a one-parameter family of parallel lines. A cylinder whose cross section is an ellipse, parabola, or hyperbola is called an elliptic cylinder, parabolic cylinder, or hyperbolic cylinder respectively.
In common use a "cylinder" is taken to mean a finite section of a right circular cylinder, i.e., the cylinder with the generating lines perpendicular to the bases, with its ends closed to form two circular surfaces, as in the figure (right). If the cylinder has a radius and length (height) "h", then its volume is given by:
and its surface area is:
Therefore, without the top or bottom (lateral area), the surface area is:
With the top and bottom, the surface area is:
For a given volume, the cylinder with the smallest surface area has . For a given surface area, the cylinder with the largest volume has , i.e. the cylinder fits in a cube (height = diameter).
Having a right circular cylinder with a height units and a base of radius units with the coordinate axes chosen so that the origin is at the center of one base and the height is measured along the positive x-axis. A plane section at a distance of units from the origin has an area of square units where
or
An element of volume, is a right cylinder of base area square units and a thickness of units. Thus if "V" cubic units is the volume of the right circular cylinder, by Riemann sums,
Using cylindrical coordinates, the volume can be calculated by integration over
Cylindric sections are the intersections of cylinders with planes. For a right circular cylinder, there are four possibilities. A plane tangent to the cylinder, meets the cylinder in a single straight line. Moved while parallel to itself, the plane either does not intersect the cylinder or intersects it in two parallel lines. All other planes intersect the cylinder in an ellipse or, when they are perpendicular to the axis of the cylinder, in a circle.
An elliptic cylinder, or cylindroid, is a quadric surface, with the following equation in Cartesian coordinates:
This equation is for an elliptic cylinder, a generalization of the ordinary, circular cylinder (). Even more general is the generalized cylinder: the cross-section can be any curve.
The cylinder is a "degenerate quadric" because at least one of the coordinates (in this case ) does not appear in the equation.
An oblique cylinder has the top and bottom surfaces displaced from one another.
There are other more unusual types of cylinders. These are the "imaginary elliptic cylinders":
the "hyperbolic cylinder":
and the "parabolic cylinder":
Vacuum
A vacuum is a place where there is no matter, not even air. Sound cannot move in a vacuum. No place has a perfect vacuum, because a small number of particles remain, even in outer space.
A space where only some of the air is removed is also called a vacuum. The space then has lower pressure, even though most of the air remains.
Vacuum is needed for some kinds of machines used for industrial production. Vacuum pumps are used to pump air out of a vacuum chamber. It is not possible to create 100% vacuum, but some vacuum pumps are able to create 99.9999% vacuum. This is called "hard vacuum". Most industrial purposes do not need hard vacuum.
Industrial vacuums are mainly used in:
Vacuum chambers are also used in many scientific experiments in laboratories. Some experiments in physics and chemistry need hard vacuum to keep any air or other gases from interfering with delicate surfaces or chemicals that can react.
Catherine Howard
Catherine Howard (c. 1521 – 13 February 1542) was the Queen of England from 1540 until 1541, as the fifth wife of Henry VIII of England.
Catherine Howard (also spelled "Katherine") was born in about 1521, but the exact date is unknown. She was the tenth child of Lord Edmund Howard and Joyce Culpepper. Her father was the second son of the Duke of Norfolk. She was a cousin to Anne Boleyn, who was the second wife of Henry VIII.
Catherine's family was poor so they sent her to live with her step-grandmother, Agnes Tilney. Agnes Tilney, the Duchess of Norfolk, had a large household, but it was not very strict. Catherine could read and write, but she was the least-educated of Henry VIII's wives.
Catherine became a lady-in-waiting to Queen Anne of Cleves in 1539 or 1540, when she was about 18 years old. Anne of Cleves was the fourth wife of Henry VIII. The king did not like Anne, and said she was not as pretty as he had hoped for and also called her a Flanders mare (horse). He soon fell in love with Catherine.
In July 1540, after Henry had annulled his marriage with Anne of Cleves, Henry and Catherine got married at Oatlands Palace, which is in Surrey.
Henry VIII loved his young bride and gave her lots of rich presents, such as jewels and expensive clothes. He called her his 'rose without a thorn' and the 'very jewel of womanhood'. Her motto was ""Non autre volonté que la sienne"" (French) or "No other wish but his". However, Catherine was not happy in her marriage. Her husband was very fat (he was about at the time), much older than she was, and had an ulcer on his legs. She started becoming acquainted with a man named Thomas Culpepper.
Rumors that Catherine was unfaithful began to be repeated at court. Then Francis Dereham told