4to40.com

What is unbreakable glass made of, and is it really unbreakable?

The presence of micro cracks on the glass surface (called Griffith’s micro cracks) makes glass breakable under tension or impact. Such micro cracks are unavoidable as the glass surface comes under tension while cooling from a high temperature into various shapes. However, one can increase its impact resistance by various methods, so it can withstand even the impact of a …

Read More »

What is time dilation?

In the theory of special relativity, the slowing down of a clock as determined by an observer who is in relative motion with respect to that clock, is called time dilation. In this phenomenon, a person finds a clock (or other time device) similar or identical to their own, ticking at a slower pace, making the observer believe that time …

Read More »

What is thigmotropism?

Thigmotropism is the growth of a plant around a support. Tropism is a phenomena by which a plant, usually climber like money plant and ivy, responds to a stimulus. Stems of the pea plant, for instance, are weak and have coil-like structures called tendrils. When tendrils approach a support (stick), a phytohormone called auxin is released in the side of …

Read More »

What is the world’s remotest inhabited country?

In the South Atlantic Ocean, about half way between Africa and South America, are the British islands of Tristan da Cunha. Their nearest neighbour is St Helena, another British island 2,120km (1,317 miles) away. In 1961, a volcanic eruption forced the Tristan islanders to leave for Britain. But life in crowded Britain lacked appeal and most of them went home …

Read More »

What is the white cloud formed when a plane breaks through the sound barrier?

A sharp rise in aerodynamic drag, occurs when a plane reaches the speed of sound. For an aircraft flying at subsonic speed, the pressure waves generated by it extend in all directions, and, outspeeding the craft, transmit the disturbance uniformly. However, for supersonic speeds, the pressure field is confined to an area extending in a Mach cone from the rear …

Read More »

What is the Venus Project?

The Venus Project is an organization that promotes and advocates American futurist Jacque Fresco’s visions of the future with the aim to improve society by moving towards a global sustainable social design that they call a “resource-based economy”. Such a system incorporates sustainable cities and values, energy efficiency, collective farms, natural resource management and advanced automation, focusing on the benefits …

Read More »

What is the unit of magnetic power?

Earlier, the power of a magnet was only measured in units of gauss. Gauss defines the number of lines of magnetic (flux density) per square centimetre emitted from the surface of the magnet. Today, it is measured in gauss-oersted energy units (GOe). While gauss refers to the number of lines of flux emitted from a magnet, oersted is the unit …

Read More »