Recent questions tagged everyday-science

Description : Why is the water in an open pond cool even on a hot summer day?

Last Answer : Answer: As the water evaporates from the open surface of a pond, heat is taken away in the process, leaving the surface cool.

Description : Why does kerosene float on water?

Last Answer : Answer: Because the density of kerosene is less than that of water. For the same reason cream rises in milk and floats at the top.

Description : Why does moisture gather outside a tumbler containing cold water?

Last Answer : Answer: The water vapour in the air condenses on cooling and appears as droplets of water.

Description : Why does ice float on water?

Last Answer : Answer: The weight of the ice block is equal to the weight of the liquid displaced by the immersed portion of the ice.

Description : Why does a small iron sink in water but a large ship float?

Last Answer : Answer: The weight of water displaced by an iron ball is less than its own weight, whereas water displaced by the immersed portion of a ship is equal to its weight (Archimedes? Principle).

Description : Why does blotting paper absorb ink?

Last Answer : Answer: Blotting paper has fine pores, which act like capillaries. When a portion of blotting paper is brought in contact with ink, ink enters the pores due to surface tension (capillary action f liquids) and is absorbed.

Description : Why is one?s breath visible in winter but not in summer?

Last Answer : Answer: In winter, water vapor contained in the breath condenses into small droplets, which become visible but in summer they are quickly evaporated and not seen.

Description : Why does a swimming pool appear less deep than is actually is?

Last Answer : Answer: The rays of light coming from the bottom of the pool pass from a denser medium (water) to a rarer medium (air) and are refracted (bend away from the normal). When the rays return to the surface, they form an image of the bottom of the pool at a point, which is little above the real position.

Description : Why is a rainbow seen after a shower?

Last Answer : Answer: After a shower, the clouds containing water droplets act like a prism through which the white light is dispersed producing a spectrum.

Description : Why is water from a hand pump warm in winter and cold in summer?

Last Answer : Answer: In winter, the outside temperature is lower than that of water flowing out of the pump, and therefore, the water is warm. Whereas in summer, the outside temperature is higher than the water of the pump, and therefore, it feels cold.

Description : Why is a compass used as an indicator of direction?

Last Answer : Answer: The magnetic needles of a compass under the influence f the earth?s magnetic field lie in a north-south direction. Hence, we can identify direction.

Description : Why does an ordinary glass tumbler crack when very hot tea or milk is poured in it?

Last Answer : Answer: When a hot liquid is poured into a tumbler, the inner layer of the tumbler gets heated, it expands before the outer layer and an unequal expansion of both layers causes the tumbler to crack.

Description : Why does a man fall forward when he jumps out of a running train or bus?

Last Answer : Answer: He is in motion while in the train or bus. When he jumps out, his feet comes to rest while touching the ground but his upper portion which is still in motion propels him forward.

Description : Why does an electric bulb explode when it is broken?

Last Answer : Answer: The bulb encompasses partial vacuum and as it breaks, air rushes in causing a small explosion.

Description : Why does smoke curl up in the air?

Last Answer : Answer: Smoke contains hot gases which being lighter in weight, follows a curved path because of the eddy currents that are set up in the air.

Description : Why do we lean forward while climbing a hill?

Last Answer : Answer: In order to keeps the vertical line passing through our centre of gravity always between our feet, which is essential to attain equilibrium or stability.

Description : Why does a balloon filled with hydrogen rise in the air?

Last Answer : Answer: Weight of hydrogen is less than the weight of air displaced by it. In balloons hydrogen is normally filled because it is lighter than air.

Description : Why are water or mercury droplets always round when dropped on a clean glass?

Last Answer : Answer: The surface of a liquid is the seat of a special force as a result of which molecules on the surface are bound together to form something like a stretched membrane. They tend to compress the ... which causes the drop to take a round shape as for a given mass he sphere has minimum volume.

Description : Why cannot a copper wire be used to make elements in electric heater?

Last Answer : Answer: Copper melts at 108.3^0C and forms a black powder on reacting with atmospheric oxygen. For heater elements a metal should have more resistance to produce heat.

Description : Why is a small gap left at the joint between two rails?

Last Answer : Answer: To permit expansion of rails due to heat generated by friction of a moving train.

Description : Why does a corked bottle filled with water burst if left out on a frosty night?

Last Answer : Answer: Because of low temperature the water inside the bottle freezes. On freezing it expands, thereby its volume increases and pressure is exerted on the walls.

Description : Why do we bring our hands close to the mouth while shouting across to someone far away?

Last Answer : Answer: By keeping hands close to mouth the sound is not allowed to spread (Phenomenon of diffraction of sound) in all direction, but is directed to a particular direction and becomes louder.

Description : We never see birds urinating.

Last Answer : Ans: The birds do not have a urinary system like other living beings which possess urinary excretory organs. In the birds the urine is excreted from body without special organs.

Description : A geostationary satellite appears standstill to a viewer on the equator of earth.

Last Answer : Because these satellites are in the geosynchronous orbit (an orbit around the Earth with an orbital period matching the Earth's sidereal rotation period) Geostationary orbit is a type of geosynchronous orbit that is directly above the equator

Description : The manholes covers are generally round.

Last Answer : It is impossible to drop a round lid into a smaller round hole. It is because round is the only shape that if turned or flipped over, it still retains the same length across its center. If you used ... it on its edge. A round cover contains less metal than a same-sized cover of any other shape.

Description : The dogs pant, the birds open their mouth and the elephants move rapidly their ears.

Last Answer : I think all of these do not sweat, they use the above mentioned mechanisms to cool themselves

Description : Define RECEPTORS in man. Name different receptor organs in human body.

Last Answer : In a sensory system, a sensory receptor is a sensory nerve ending that recognizes a stimulus in the internal or external environment of an organism. Following are the different sensory ... to temperature, either heat, cold or both  Electromagnetic Receptors's respond to electromagnetic waves

Description : Define the following a) Amphibion b) Synchronous satellite c) Big Dipper d) Fermentation e) Millennium Bug

Last Answer : (a) Amphibion cold-blooded vertebrate animal able to live both on land and water (b) Synchronous satellite A satellite in a synchronous orbit A synchronous orbit is one in which an orbiting object ... an inability in older computing software to deal correctly with dates of 1 January 2000 or later.

Description : Write briefly (a)Allotropy (b) Nebula (c) Enrichment of Uranium (d) Aqua Regia (e) Greenhouse effect (f) Igneous rocks

Last Answer : (a)Allotropy existence of a chemical element in two or more different forms For example, the element carbon has two common allotropes: diamond, where the carbon atoms are bonded together in a ... igneous rocks have been described, most of them formed beneath the surface of the Earth's crust.

Description : Sun is glorious star in our sky. Write down its characteristics with reference to the following date:

Last Answer : (a) Distance from earth 149,600,000 kilometers, or 92,960,000 miles (b) Mean distance from center of galaxy 26,000 light-years (c) Velocity around centre of galaxy 251 km ... the core temperature reaches around 100 million kelvins and will produce carbon, entering the asymptotic giant branch phase

Description : X-rays and Gamma rays

Last Answer : X-Rays - High energy electromagnetic radiation of wavelengths in the range 10 to 0.1 nanometres. X-rays are extra-nuclear and have two sources: (1). A characteristic (e.g.K- or L-) Xray photon is ... originate in the nucleus of atoms. A gamma ray is a photon, i.e. a discrete packet of many waves

Description : Periscope and perimeter

Last Answer : Periscope - optical scope that allows one to see objects that are located above one's line of sight perimeter - outer boundary of a figure or area; total length of the outer boundary

Description : Lava and Magma

Last Answer : Lava - molten rock expelled from a volcano; solidified volcanic rock Magma - molten rock beneath the earth's crust from which igneous rocks are formed (Geology)

Description : Myopia and Hypropia

Last Answer : Myopia - nearsightedness, condition of the eyes in which objects that are far away cannot be seen clearly (Ophthalmology); lack of insight and forethought Hyperopia - far-sightedness, ability to see distant objects more clearly than near ones

Description : Smog and Smoke

Last Answer : Smog - mixture of smoke and fog Smoke - visible vapor given off by burning material;

Description : Heavy water and hard water

Last Answer : Heavy Water - water with a higher average molecular weight than ordinary water, water used for cooling the core of an atomic reactor Hard Water - water containing a high concentration of minerals and calcium

Description : Umbra and Penumbra

Last Answer : Umbra - area of the shadow of an eclipse, dark center of a sunspot Penumbra - partly lighted area around any shadow

Description : Define ENERGY. Name four renewable sources of energy. How can our country come out of Energy Crisis?

Last Answer : Energy: In physics, energy ", is a scalar physical quantity that describes the amount of work that can be performed by a force, an attribute of objects and systems that is ... Administrative Improvement. -Utilization of largest deposits of coal. -Renewable sources of energy. -Public Awareness.

Description : Write briefly a. Supernova: b. Radioactivity c. Laser: d. Semiconductors: e. Geothermal Energy

Last Answer : a. Supernova: star increasing suddenly in brightness. b. Radioactivity: spontaneous disintegration of atomic nuclei, with the emission of usu. penetrating radiation or particles. c. Laser: device ... a computer program and intended to corrupt the system or destroy data. g. Pasteurization:

Description : Antibiotics & Vaccination:

Last Answer : An antibiotic is a substance or compound that kills or inhibits the growth of bacteria. Antibiotics belong to the group of antimicrobial compounds used to treat infections caused by microorganisms ... is considered to be the most effective and cost-effective method of preventing infectious diseases.

Description : Telescope & Microscepe:

Last Answer : A telescope is an instrument designed for the observation of remote objects by the collection of electromagnetic radiation. A microscope is an instrument for viewing objects that are too small to be seen by the naked or unaided eye.

Description : Fertilization & Pollination:

Last Answer : Fertilization is a process in sexual reproduction that involves the union of male (sperm) and female (ovum) gametes (each with a single, haploid set of chromosomes) to produce a ... process by which pollen is transferred in flowering plants, thereby enabling fertilisation and sexual reproduction.

Description : Star and Planet:

Last Answer : A staris a huge ball of hot glowing gases whirling in space. Our sun is a star and the only one close enough to earth for us to see its ball shape. all are made up of the same two gases, ... , stars seem to twinkle. This is because of the movement of layers of air between the stars and the earth.

Description : Fission and Fusion:

Last Answer : Fission splits a massive element into fragments, releasing energy in the process. Fusion joins two light elements, forming a more massive element, and releasing energy in the process.

Description : The weight of the object is less at the equator than at the poles.

Last Answer : Ans: At equator, the distance from the earth's center is greater than any other point of the earth's surface. Since, weight is defined as the force with which a body is attracted towards the earth's ... the force applied. Hence, the object's weight is lightest at the earth's equator, than at poles.

Description : Vitamin D is the essential component of the Body.

Last Answer : Ans: Vitamin D is responsible for the absorption of calcium and phosphorus in the bones..

Description : Mars is called red planet.

Last Answer : Ans: Mars is called the red planet because its colour is red due to the desert like surface.

Description : Why climbers get their food by climbing on other trees ?

Last Answer : Ans: By climbing on other trees, they get close to the light source.

Description : define the following: (1) Vaccine: (2) Antibiotic: (3) Solar eclipse: (4) Exothermic:

Last Answer : (1) Vaccine: an antigenic preparation used to establish immunity to a disease. (2) Antibiotic: a drug that kills or prevents the growth of bacteria. (3) Solar eclipse: occurs when the moon passes ... sun. (4) Exothermic: A reaction that releases energy in the form of heat is called exothermic.

Description : Briefly discuss the classification of plants giving suitable examples:

Last Answer : There are nearly half a million species of plants on the earth. With the exception of few , all of them need three basic ingredients to survive : air , light and water . Plants are found ... angiosperms include most other trees , the flowering plants, the grasses , crop plants , vegetable and weeds.