A sinkhole (in Karst topography) is a hole in the ground that forms when water dissolves surface rock. Often, this surface rock is limestone, which is easily eroded, or worn away, by the movement of water.
Formation of a Sinkhole: In a landscape where limestone sits underneath the soil, water from rainfall collects in cracks in the stone. These cracks are called joints. Slowly, as the limestone dissolves and is carried away, the joints widen until the ground above them becomes unstable and collapses. The collapse often happens very suddenly and without very much warning. Water collects in these collapsed sections, forming sinkholes.
Sinkholes also form when the roofs of caves collapse. Sinkholes are often funnel-shaped, with the wide end open at the surface and the narrow end at the bottom of the pool.Sinkholes vary from shallow holes about 1 meter (3 feet) deep, to pits more than 50 meters (165 feet) deep.
Thermoset, or thermosetting, plastics are synthetic materials that strengthen during being heated, but cannot be successfully remouldedor reheated after their initial heat-forming. This contrasts withthermoplastics, which soften when heated and harden and strengthen after cooling. Thermoplastics can be heated, shaped and cooled as often as necessary without causing a chemical change, while thermosetting plastics will burn when heated after the initial moulding.
Presently, there are 226 flood forecasting stations consisting of 166 level forecasting stations for villages and towns and 60 inflow forecasting stations for reservoirs/dams/barrages in the country. Existing flood forecasting network covers 22 States / Union Territories and 19 major river basins / sub-basins in the country.
Proxima Centauri is the nearest star, and on August 24, 2016 astronomers announced it likely has a planet. This star is the nearest of a triple star system, which we on Earth see with the eye alone as the single star Alpha Centauri, visible from Earth's Southern Hemisphere
Rejuvenation occurs when the river?s base level falls (i.e. when sea level falls). This can be a consequence of either a fall in the amount of sea water or the land rising. Incised meanders are meanders which are particularly well developed and occur when a river?s base level has fallen giving the river a large amount of vertical erosion power, allowing it to down cut. Hence, 2nd statement is correct.
There are two types of incised meanders, entrenched meanders and ingrown meanders.As they are products of rejuvenation, they are not formed in mature stage of a river
Glaciers cut distinctive U-shaped valleys with a flat floor and steep sides. These are an example of a glacial erosion landform.
Example: As the main glacier erodes deeper into the valley, the tributary is left higher up the steep sides of the glacier.
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon and the Sun and the rotation of Earth.
Statement 2 is also correct. But it is not the correct explanation for the 1st statement.
Electronic Flash differs from the consumable bulb flash in important aspects. Instead of creating light by burning up in an atmosphere containing oxygen, a consumable material (each bulb being used therefore only once), it produces a brilliant incandescent by discharging a current for a brief instant through a rarified gas, usually xenon. The gas glows every time the discharge is made through it but it is not consumed, so that many thousands of flashes are obtainable from a single tube, which helps to offset the much higher cost of the initial apparatus.
Nirbhay missile is India's first indigenously designed and developed long range sub-sonic cruise missile.It is designed and made by DRDO (Defence Research & Development Organisation).The Nirbhay missile can be deployed from multiple platforms.
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