Physics

Physics regards the physical aspects of the natural world. It includes topics that deal with forces on different bodies within the universe and phenomena that explain how the universe works.

Asked in Meteorology and Weather, Physics

Why is the sky blue?

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Because during day time our atmosphere scatters red light and bluish appearance is
Asked in Physics, Example Sentences

How do you use attenuation in a sentence?

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After his heart transplant, he was given special medicine to prevent rejection, these drugs are to be taken daily in order for attenuation to take place and to attenuate the immune response and to keep the body from rejecting its new heart. Installing this new piece of equipment will let through the lower frequencies, therefore achieving attenuation.
Asked in Physics, Engineering

What device or instrument is used to measure air pressure?

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There are several options depending on the type of air pressure being measured: In the 1800's ships used a weather glass - a simple barometer - to measure changes in air pressure. To measure atmospheric (ambient air) pressure, a barometer is used. (It may be either an aneroid or a mercury type of barometer.) For tires, it's a tire pressure gauge. In industrial processes and boilers the gauge is frequently called a manometer. For pressure vessels it is a Bourdon gauge.
Asked in Physics, Computers

What is the Example of digital quantity?

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A digital quantity example is provided by any digital microprocessor display where a discrete number is provided and the actual value is an irrational number. Some examples are the computer display of the values of pi, the square root of 2, the quotient of 3/19, or any other irrational number. A computer basically works with the integers 0 and 1, so it is a "digital" machine (it cannot deal with 3/19, or pi, etc with perfect accuracy).
Asked in Biology, Physics, Social Sciences

What is the movement of organisms from one place to another?

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Transportation is the movement of animals from one place to other.
Asked in Physics, Space Travel and Exploration, Science Experiments, Sound Waves

What is the speed of ultrasound waves in the air?

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The 'normal' speed of sound is 340 m/s in dry air at room temperature and pressure. From your question, it appears we should differentiate the terms "ultrasonic" and "supersonic". Ultrasonic relates to sonic frequencies higher than 20 KHz, i.e. beyond audible range. For a given gas, the speed of sound is independent of the frequency of the sound measured and also independent of the density of the gas. Supersonic relates to a speed of an object greater than the normal speed of sound (340 m/s in air at STP) and usually the phenomena associated with it. The speed of sound is also a functionof the medium through which it's passing. For example, the speed of sound through water is 1,500 m/s, and is slightly over 5,000 m/s in iron. So to answer your question, the speed of ultrasound in airis340 m/s for the reasons given.
Asked in Physics

Which term describes the tendency of an object to resist a change in motion?

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An object's tendency to resist a change in its state of motion is called inertia. This is the basis of Newton's Laws of Motion; "An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.". The state of motion refers to the object's velocity, which is the the speed and direction. One quantifies inertia as the quantity of mass of an object. On can say that the mass of an object is a measure of how much an object resists change in its motion. The more mass an object has, the more inertia it has. That's why it is harder to push a 3 ton box as opposed to a soccer ball, or something lighter.
Asked in Physics, Botany or Plant Biology

Science investigatory project of avocado leaves?

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You can try to find a use for avocado leaves like observing if it is good at repelling mosquitoes or if it will make a fire last longer or something like that.
Asked in Biology, Physics, Chemistry

Which science is the most complex chemistry or biology or physics?

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Biology is the most complex because it deals with living organisms and number of known organisms is more than two and a half million while un-described species are estimated up-to 30 million . each organism is different from other and has its peculiarities . Chemistry deals with matter, with 92 natural element and nearly thirty synthetic elements . Number of organic molecules is quite large but much less as compared to species.
Asked in Physics, Toothbrushes

What kind of a simple machine is a toothbrush?

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A toothbrush is not a simple machine, it does not work on the principle of levers, effort, and load. It's not a machine at all in mathematical terms. A "machine" is that which performs "work", i.e. transfers or converts energy. You arm moving the toothbrush is a machine by this definition, however.
Asked in Science, Physics, Chemistry, Chemical Bonding

Why does water have a high and specific heat capacity?

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First, we need to know a little bit about water. Water is a polar molecule because oxygen bears partial negative charge and hydrogen bears partial positive charge. This results in extensive hydrogen bonding in water molecules between slightly negative oxygens and slightly positive hydrogens. Second, we need to remember that temperature is another way of saying the average kinetic energy of particles - the higher the temperature, the faster they move, in the case of gases and liquids, or vibrate, in the case of solids. Third, heat capacity is the ability of matter to absorb thermal energy. One calorie is defined as the amount required to heat a gram of water one degree Centigrade. That same calorie will heat a gram of gold 33 degrees. Water's specific heat is defined as 1. The specific heat of gold is therefore .03. Water has a high specific heat because there are quite a few ways water can store heat. 1. Moving along three axes 2. Rotating the "V" shaped molecule in three different directions 3. Hydrogen atoms vibrating back and forth like a tuning fork 4. Hydrogen atoms vibrating up and down along their H-O axis. Finally, the heat of fusion of water is 80 calories per gram, and the heat of vaporization for water is 540 calories. So ice can absorb 80 times as much heat while melting as the same mass of water. Water absorbs 540 times as much heat while turning into water vapor as the same mass of water absorbs. Both phase changes occur at constant temperature, 0 Centigrade and 100 Centigrade respectively. Look up phase change graph for water to see the interesting line.
Asked in Physics, Nuclear Physics, Particle Physics

Matter attracts other matter does antimatter will repel the antimatter?

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Antimatter observes and obeys the same fundamental forces that matter does: gravity electromagnetism weak interactive strong interactive A positron, which is the anti-particle of the electron, for example, has the same mass as an electron and experiences the same attraction to all other matter (gravity) as an electron. That same positron is repelled by positively charged particles and attracted to negatively charged particles (electromagnetism).
Asked in Physics, IQ, Stephen Hawking

What is Stephen Hawking's IQ?

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Although Professor Hawking discounts the value of numerical IQ's, he admitted that his own is likely very high (it has been suggested as 160 or more). He also said that "People who boast about their IQ's are losers". (see link to 2004 interview) ---a possibly dramatized anecdote from Introducing Stephen Hawking (2006)--- Near the end of his term at Oxford and no doubt beginning to feel the effects of ALS, Hawking took a terrible fall down a staircase in the university hall. As a result, he temporarily lost his memory. He could not even remember his name. After several hours of interrogation by his friends, he finally returned to normal but was worried about possible permanent brain damage. To be sure, he decided to take the Mensa test for individuals with superior intelligence. He was delighted to find that he passed with flying colours, scoring between 200 and 250!
Asked in Physics, Mechanics, Newtons Laws of Motion

What is the formula for calculating acceleration?

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Acceleration There are a few. The most famous is a = F/m, where F is the net force applied to a mass, m. Acceleration is also the change in velocity, (Delta-V), divided by the change in time, (Delta-t). So, a = Δv/Δt. For example, if an object's velocity changes from 10 meters per second to 20 meters per second in five seconds, its acceleration is (20-10)/5 = 2 meters per second per second, or 2 meters per second squared (m/s2). For circular motion, centripetal acceleration is v2/r, where v is the linear velocity of the rotating object and r is the radius of its circular path. Equations in a nutshell Constant Acceleration a = Δv/Δt = (vfinal - vinitial) / (tfinal - tinitial) a = (v2-u2)/2s a = 2(s - ut)/t2 where a=acceleration (m/s2) v=final velocity (m/s) u=initial velocity (m/s) t=time (s) s=distance (m). OR a=(v-vo)/t a=acceleration (m/s2) v=final velocity (m/s) vo=initial velocity (m/s) t=time (s). Newton's Second Law F = ma, thus, a = F/m Centripetal Acceleration ac = v2/r Warning: Calculus Speak: Acceleration is the second derivative of position with respect to time: d2x / dt2, which makes it the first derivative of velocity: dv / dt. Therefore, the acceleration is the slope of the curve on the velocity-versus-time graph. Thus: a = dv / dt = d2x / dt2 Acceleration is a quaternion with real and vector parts: a= (V^2/R - cDel.v)) + (dcv/dR + cDelxv + V^2/R r) a= (V^2/R - cV/R cos(v)) + (dv/dt + cv/R sin(v) + V^2/R r) where R=ct and dR=cdt. cv/Rcos(v) is the Centrifugal Acceleration a part of the real accelerations in the first parenthesis. The second parenthesis contains the vector accelerations. Acceleration = F/m, where F is the net force applied to a mass, m. a=f/m, acceleration in terms of velocity. a = v - u/t Delta Velocity divided by Time. A = ΔV ÷ T Acceleration is worked out by (final speed - initial speed)/ time taken for change in speed a = v2-v1/ t2-t1 Strictly you should say velocity ie the speed in a certain direction. Youalso have the formula f=ma which tells you that the force needed to get something moving will be the mass of the object multiplied by the accelertion you want to achieve; so from this formula if you know force and mass you can work out acceleration. The formula for acceleration is: Vf-(Vi)/t ie. change in velocity per unit time. Instantaneous acceleration in its differential form is d2x/dt2 where x is a function of time t. Acceleration is the time rate of change of velocity. That is, acceleration = dv/dt (v - velocity ; t - time) Or simply acceleration = change in velocity / time
Asked in Physics, Chemistry, Atoms and Atomic Structure

What is the temperature of a lighter flame?

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The temperature of a Bic lighter flame is 1977 C or 3590.6 F.
Asked in Solid State Physics, Physics

What is dislocation density?

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Dislocation density is the areal density of dislocations intersecting a plain, usually the free surface, given as number per cm2. It may also be the volume density of dislocation line segments, given as the total length of dislocations divided by the containing volume (also 1/cm2), but this is rarely used in semiconductor physics, and more frequently found in engineering. Dislocation density is typically measured by etching the free surface to form pits around the location at which the dislocation breeches the surface, and is termed etch pit density, or EPD.
Asked in Physics, Math and Arithmetic, Weight and Mass, Gravity

What is mass divided by weight?

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Answer #1: It's (1) divided by (the acceleration of gravity in the place where that mass has that weight): weight = mass x g (where g is the acceleration due to gravity) ⇒ mass/weight = mass/(mass x g) = 1/g On the earth, g ≈ 9.81 ms-2 ⇒ mass/weight ≈ 1/9.81 ms-2 ≈ 0.102 m-1s2 On the moon, g is approx 1/6 that of the earth, ⇒ mass/weight ≈ 6/9.81 ms-2 ≈ 0.612 m-1s2 If the questioner really meant weight divided by mass it gives the acceleration due to gravity in that place otherwise I'm not sure of a use of knowing the reciprocal of the acceleration due to gravity that the questioner asked. ============================= Answer #2: If you ask a scientist, that's true answer in the sense that a mass M experiences a gravitational force Mg and if you measure weight in units of force (which nobody does). But anyone else would be surprised to learn that a mass M (say 10 grams) would have a weight of anything else but M grams (10 grams). Sometimes expressed as "grams weight" often just grams for short. If you pick up a Kilogram, even a scientist would say "its weight is 1 kilogram". The gravitational force on it is 1g, so if you let it go it will accelerate at a rate force over mass, which is g. So the answer depends on your units of mass and weight. That's why science lessons tend to avoid use of "weight". In outer free space mass would be measured by (say) tension in the string if you whirl it on the end of it around your head, but the weight (measured by a spring balance) would be zero (precisely as described in the first answer above, with g=0). ============================== Answer #2.1: The problem with discussing mass and weight in the same units, and the reason that this masked contributor is waging a one-man battle to make the distinction recognized and acknowledged by users of this website, is the new problem that you have now that the space age is here. As long as we were all irrevocably bound to the Earth, one kilogram of mass would always weigh one kilogram, if you like it that way. We could afford to be sloppy about it, with hardly one out of ten men-on-the-street knowing or caring about the difference, and nobody ever had a problem with it. But now that some of us have already slipped these surly bonds ... and among the general population, the younger you are, the better the chance that you will do so one day before you're done ... those who ignored the distinction begtween mass and weight all through school, or never even encountered it there, are poised to step into an inconvenient pile. Because as soon as you pack for your trip to anywhere else away from Earth, and take along your lucky kilogram, you're due for a shock when you step out at your destination: Your kilogram doesn't "weigh" a kilogram there. It weighs something else. If you're on the moon, for example, your kilogram weighs 0.165 kilogram ! That's the shock I'm trying to avoid, because if you think the straight dope is too complex for people to handle now, you haven't seen anything yet.
Asked in Physics, Quantum Mechanics

Why are leptons divided into families?

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Leptons are divided into three families with 4 particles (2 particles, plus their two anti-particles) in each family. In the electron family we have the electron, positron, electron neutrino and electron anti-neutrino. Each family has a higher mass than the one before it so the tauon is heavier than the muon which is heavier than the electron. The physical reason for there being three families is completely unknown and will probably win you a Nobel prize if you can figure it out!
Asked in Science, Physics, Temperature

What instrument measures temperature?

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Most commonly, a thermometer. Related Information: Thermometers are used to measure the increase or decrease in the temperature of a system as it gains or loses internal energy. An alcohol-in-glass thermometer has been the most common personal instrument used to measure temperature. Mercury thermometers are still around but are no longer offered for sale. Today, digital devices are available that scan the forehead or ear. Some other devices used to measure temperature are: Radiation pyrometer, for extremely high temperatures; Glass thermometer: mercury or alcohol; Thermocouple; Thermistor (thermal resistor) Bimetallic strip; Bimetallic spiral; Platinum resistance thermometer (a resistance detector); Examples: A mercury in glass thermometer uses mercury liquid contained within its glass structure to be subjected to heat. the heat causes the mercury fluid to expand along the glass tube and the total amount of expansion can be seen as a measure along the accurate scale of indication. This is a direct indication of the effects of temperature. A more complex method of measuring temperature could be a thermocouple measuring device. A thermocouple consists of 2 dissimilar types of metal materials in the form of wires , which are joined at 1 end by weld/ fusion. this single joined end is called the hot junction. The other end of the 2 wires are then terminated at separate junctions; as in a electronic terminal block. This end of the 2 wires can be called the cold junction. For most accurate temperature measure, I think temperature sensor is the first choice.
Asked in Science, Physics

Why are light and heat not considered matter?

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What i understand is that there is noting call "Light" or "Heat" its just the "Space",. "Space" created between sub atomic particles and atom we understand and call it "Light" and our eye recognizes it - and "Space" created between atom, molecules and cells we feel it and call it "Heat" - our cells / skin feels it IF "Light" is a "particle" or "wave" then you should not see the same star from just one feet away - your eye should loose the particle as it should have gained a little space during its million kilometer journey. Rajeev. Colombo. OLD reply >> Light (including all forms of electromagnetic radiation) is not considered matter because it has no rest mass. Heat doesn't have rest mass either, in fact it is nothing other than the random motion of atoms. These things have energy. They interact with other stuff. But they aren't matter because they aren't what material objects are made up of. Alternatively: Light and heat are not tangible things that you can see, touch or weight. One can not chemically isolate atoms of heat or light. There is no official answer to this question because everyone just takes is as a given fact.
Asked in Physics, Nuclear Physics, Atoms and Atomic Structure, Particle Physics

Are quarks nucleons?

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No, quarks are not nucleons. A nucleon is a term (in physics) that is given to either of the two component particles of an atomic nucleus: the proton and the neutron. Both protons and neutrons are composite particles from the family of hadrons, and hadrons are made up of quarks.
Asked in Physics

Who invented the law of displacement?

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The mathematician Archimedes of Syracuse. The most common story (which was first told by Vitruvius but doesn't pop up in Archimedes' known works) goes that King Hiero II had a votive crown forged for a temple, and he supplied the pure gold the goldsmith was to use. However, when he got the crown, the King asked Archimedes to determine whether the goldsmith had used all of the gold supplied or substituted silver for some of the gold. Archimedes couldn't melt the crown down into a regular shape to find its density, because he had to leave the crown intact, so he puzzled over the problem for some time. While taking a bath one day, he noticed that the water level rose as he stepped in, and realized that he could use this effect to solve the problem, and supposedly ran through the streets screeching "εὕρηκα!" (heureka!, Greek for "I've found it!") naked. When he performed the test with the crown, he found that the goldsmith had indeed substituted silver for some of the gold.
Asked in Science, Physics

Density symbol in physics?

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By convention we use the lower-case Greek letter, rho (ρ.), for the density symbol in physics.
Asked in Physics, Electromagnetic Radiation, Waves Vibrations and Oscillations

What equation relates frequency and wavelength and speed of light?

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(Frequency) x (Wavelength) = Speed of light. Note carefully that the "speed of light" in the equation above is the speed of light in the medium that the wavelength is measured in. In vacuum it will be the famous constant "c", but when light travels through any sort of material it's speed is slowed and its wavelength shortened by a factor called the refractive index of the medium. Because wavelength and speed are reduced by the same factor the equation still holds. Light's frequency is not affected by the medium.
Asked in Physics, Psychology

Who is the world's first psychologist?

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The Greek philosopher Aristotle can be regarded as being the world's first psychologist because he wrote a book called 'De Anima', about the soul, and the soul is part of the subject matter of the original meaning of the word 'psychology'. But conventionally Wilhelm Wundt, a German academic who was originally a physiologist, is regarded as the world's first psychologist because he created a psychological laboratory to which the subsequent development of psychology as a science can be traced back to the psychologists who received instruction there.