Science & Mathematics Questions & Answers

A blind hole refers to a hole that is reamed, drilled, or milled to a specified depth, thus without breaking through to the other side of the workpiece. The etymology is that it is not possible to see through a blind hole. Other types of holes also include through holes, and clearance holes. In this instance blind may also refer …

A chemical bond is the phenomenon of chemical species like atoms held together by electrostatic or electronic forces. Of the several types of chemical bonds, a special type exists in the molecule of boron hydride BH3 which exists as a dimer B2H6 molecule. It contains two types of hydrogen atoms. Four hydrogen atoms are of one type, which are used …

A 120-cell is a finite regular four-dimensional polytope with the schlafli symbol 5,3,3 . It is also known as hyperdodecahedron or hecatonicosachorn and is composed of 120 docahedra, hence it is known as 120-cell. The 120-cell has 600 vertices, 720 pentagons and 11,200 edges. It is one of the six regular polychora.

Researchers in Japan have invented a tiny brain which can act as a remote control for swarms of nanomachines. They simultated eight such nano-machines to create a ‘nano factory’. Experts say nanomachines could be used to boost the processing power of future computers. They also hope nano-machines can treat diseases. The machine is made from 17 molecules of the chemical …

A ‘tester’ is a canopy over a bed, which is supported on the pots of the bedstead or suspended from the ceiling. Formerly the word was used to described the vertical post at the head of the bed which rose to, and sometimes supported the canopy or the framework on which the canopy and curtains rested. The term ‘testour’ occurs …

A simple fortification consisted of two parts: a natural or artificial mound (motte) with a wooden tower or keep on top, and a larger area at the foot of the mound enclosed by palisades, (and later by walls and towers of masonry), called a bailey. The bailey was used for stores and huts. This outer walled space sometimes had a …

From about A.D. 800 the Norse sailors raided the coasts of northwest Europe, and the craft they used were the broad and shallow ‘longships’. The Vikings, as the Norsemen are commonly called today, set out from their creeks or fiords in Scandinavia and Denmark in early spring and late summer, and sailed away on long, bold searches for plunder. These …

What we see today are two-dimensional movies with multi-channel sound. In three-dimensional movies, viewers are required to wear special glasses which creates 3-D images of objects. ‘Chhota Chetan’ and ‘Shiva Ka Insaaf’ were such movies released two decades ago. Fourth dimension in a movie creates a different experience. Besides the 3-D effects, viewers can experience the movie through other senses …

Feeling ‘stressurised’ means the feeling of “being under pressure and stress” at the same time.

The fragrance in flowers, fruits and spices is due to the evaporation of certain volatile chemicals into the air. Flowers produce a scent which is a complex mixture of low molecular weight, with volatile compounds such as esters, is emitted into the atmosphere. No two floral scents are exactly the same because of these compounds. Plants pollinated by bees and …