Fun with physics

Hey guys, It's chilling cold here in this part of the country.What about your country?Today I am going to discuss why Some countries employ 220volt and some 110volt for household consumption.Actually the choice dates back to history when Thomas Edison and his company gave electricity at 110volt DC.Since it was employed first so people had mindset of having 110volt as safe.Although Nikola Tesla suggeted for 220volt AC but it was rejected by people.Now European countries required high voltages for big machines during world war 2,so they started giving 220volt and is continued till date.India also has 220volt power supply for household.Japan has110 volt.Now the question is which one is safer and which one is economical.Well as far as safety is concerned 110volt is much safer than 220volt but 110volt is costlier.Because for 110volt supply the wire required should have greater area of cross section so that resistance is less.Since resistance is inversely proportional to area of cross ...

Hey guys, Hope all is well with you all.This post is for class 11th students and engineering students of civil and mechanical streams.In 11th std physics book the definition of stress is simply given as the force applied per unit area on a body.Mathematically it is all good.But as far as real definition according to mechanics is concerned it is the reacting force generated per unit area in response to the external force applied.Had it been not so you cannot define the maximum stress limit of an object.Whenever stress limit is exceeded the object attains fatigue and tends towards fracture.Meaning stress of any object is bearable response to external load.Take an example of our daily life where we say the work load in office has created much stress in my life.Here stress refers to the mental stress caused due to work pressure.Here our brain is responsing to external pressure.Both the cases are similar.So understand this anology.So for a good engineering student stress is the force acti...

Hii, Next revolution in the field of energy is renewable energy.All the major developed countries have already started implementing it.One of the major source of renewable energy is solar energy.But do you know how solar panels work?The physics behind it is divided into certain stages.Solar plates employ photovoltaic cells which convert light into electricity.As light is dual in nature meaning it has particle and wave nature.Here the particle nature comes into play.Particles are nothing but photons(small packets of energy).When the photons hit the photovoltaic cell charges flow from positive to negative terminals.This electricity is DC in nature which is converted to AC with the help of inverter consisting of capacitor.Thus electricity is provided at our household loads.The excess electricity is sent to grid which provides you electricity on cloudy days.Moreover if you can transfer more energy to grid by consuming less,the government gives you subsidy also in most countries.So I hope...

Hey, This post is for everyone.From childhood we have grown up seeing our parents giving water to plants using pipes.We all have tried our hands also in that.Now we have always heard that by reducing the pipe diameter by using our fingers blocking the outlet we can increase water pressure and water will go further distance.No doubt water will travel longer distance but in this case pressure is not increasing but velocity is.Dont get confused by the formula of pressure (F=M/A) as it is applicable for solids only.In case of liquids it will follow Bernoulli's  equation stating if area is decreased kinetic energy or velocity gradient will increase and pressure gradient will decrease.So now it should be clear to all. Thanks....

Hey Kids, This post is for standard 9th students.You must be having chapter of pressure in mechanics and as of now you must have become familiar with the terms scalar and vector.If a quantity can be defined completely using only magnitude it is scalar and if direction is also required apart from magnitude then it is vector.By the definition of pressure it is Force acting per unit area.Here what happens is that no matter where you apply the pressure,its effect will be taken by the perpendicular component of that force acting on unit area.Since here it is predefined that you should take only the perpendicular component so you don't have to worry about direction.Your books might not contain above facts as these are more precisely defined in 11th standard.For the time being just know that it is scalar as it force will be perpendicular to area.You will know about vector additions,multiplications,divisions and triangle rule in higher classes.Then it will become more clear. Thanks...

Hello friends, This one is a puzzle question.There were two bears A and B having same mass m.But weight of A being higher than B. Tell the colour of A and B. .... Confused... If two things have same mass but different weight then there must be difference in acceleration due to gravity.Now,due to oblate spheroidal shape of earth the radius of earth varies at poles and equator.The radius being smaller at poles,g will be higher since g=Gm/r2.Therefore the bear must be at North or south pole.Since polar bears are found in north pole,so the colour will be white.Hence A has white colour and B black. Thanks...

Hey guys, We all have heard about transformers and we also know that what does it do.Transformers have been created to transfer required voltage at required destination.It works on the principle of mutual induction.There are two types of transformers,one step up and other step down.Step up increases voltage and step down decreases voltage.As its use differs at different situations,so transformers are given units KVA or MVA but not in watt or kilowatt.Because transformers transfer power but they don't consume it.So it is not a load but it is a machine that supplies power to loads.The users of transformers will get to know from its unit that where they should use this according to the voltage required for the particular load.So remember transformers are not loads but they provide power to loads.The load can be house'sTv,Fridge,AC,cooler,Fan etc.Depending upon the type of loads transformers are used. Thanks...

Hii, This post is about the reason why you should turn your vehicle increasing the radius of turning during taking turns which are momentarily circular in nature.It is known to all of us how to take turns but reason behind is being explained here.What happens is that while taking circular turn if you dont increase the radius it will create higher centripetal force.F=mv2/r.Now to counter this force,the frictional force provided by the road to your wheels will increase but it cannot provide the frictional force beyond its limit.After which the vehicle will skid.Another point to be considered is that velocity should also be lower otherwise the centripetal force will increase by above formula which will also increase the frictional force required.Hence you should take slow turns by increasing radius of turning.Here centripetal force and frictional force act opposite to each other. Thanks..

Hey guys, All the mechanical engineering students out there you should be familiar with above two terms before going to work in any plant.Both are nothing but temperature sensors,thermostat being used in air conditioners,refrigerators,incubators etc and Thermocouple being used in rotary kilns,boilers etc.But how do they work.Here is a brief description taken from wikipedia.For more information study them in RAC books and Electronic sensors books. A  thermostat  is a component which senses the  temperature  of a  physical system  and performs actions so that the system's temperature is maintained near a desired setpoint . Thermostats are used in any device or system that heats or cools to a setpoint temperature, examples include building  heating ,  central heating ,  air conditioners ,  HVAC  systems, water heaters , as well as kitchen equipment including  ovens  and  refrigerators  and medical and scientif...

Hey science enthusiasts, This blog is really important for students of astrophysics.Read it patiently till end. The  Laser Interferometer Gravitational-Wave Observatory  ( LIGO ) is a large-scale  physics experiment and observatory to detect cosmic  gravitational waves  and to develop gravitational-wave observations as an astronomical tool. [1]  Two large observatories were built in the United States with the aim of detecting gravitational waves by  laser interferometry . These can detect a change in the  4 km  mirror spacing of less than a ten-thousandth the  charge diameter  of a  proton . [2] The initial LIGO observatories were funded by the   National Science Foundation   (NSF) and were conceived, built and are operated by   Caltech   and   MIT . [3] [4]   They collected data from 2002 to 2010 but no gravitational waves were detected. The Advanced LIGO Project to enhance the original ...

Hello guys, This post is for the school students in their secondary school or high school.You must have come across these terms in your physics books.Both of them are often confusing to understand.Well I will clear confusion once and for all.Centripetal force is the force acting towards the centre for an object in circular motion.It always acts towards the centre.Centrifugal force is the force acting away from centre for an object in circular motion.Examples- 1.A stone tied to a thread when rotated has a force towards the centre which helps it to rotate. 2.Inside a washing machine clothes are whirled away from centre.This is centrifugal force. Actualy whenever centripetal force will be there there will be centrifugal force.Now the question is if both of them occur then why centripetal force is considered real and centrifugal pseudo.This is because the motion is accelerating leading to non Newtonian frame of reference or non inertial frame of reference.Therefore centrifugal has bee...

Hey guys, We know that to run our car from state of rest we give 1st gear.But do you know why?It is because you need greater force to start a motion than to maintain it.In mechanics for rotatory motion we use the term torque instead of force.Torque is the force which is required to start rotatory motion.Actualy torque equals force multiplied by the perpendicular distance from the point along which turning occurs.For layman consider force as torque only.Now to give your wheels the rotatory motion you need a greater torque which is possible by first gear whose size is biggest as compared to other gears.Having high gear ratio only it is possible to achieve more torque.Once you achieve this then you shift your gears to higher state which impart higher velocity.Since you cannot get high torque and high speed at the same time so we use different set of gears.The higher the gear more will be the velocity and less will be the torque.Now to climb uphill again you need  greater force(I.e t...

Hey guys, First of all let me tell you that I have read and heard about this story at various occasions but I don't guarantee you about the authenticity of this story.Having said that the logic applied in this story is scientific and the man associated has my utmost respect and none of us has the right to question his credibility.The story is as under- It was midnight and all the passengers were asleep,suddenly a middle aged man sleeping at side window seat woke up and pulled the chain.The train stopped instantly and people gathered around him and started mocking him.He said there is a crack in the railway track few metres away.People asked him are you mad,he said politely go and check then talk to me.All the railway officials and other people went there and to their astonishment there was a big crack.People asked him how did you know?He said while sleeping he observed unusual sounds coming from track which should not come under ideal conditions.Therefore he concluded that there...

Hello guys, This is just an informative post for the people of the city of joy.Everyday approximately 700000 people travel by Kolkata metro.Even I do.So just to inform you that the third line,red one is the power line of 750 volt DC.Yes it is DC not AC.I have heard people telling the voltage to be 25000volt but it is not true.So just to get your facts right it is 750 volt dc.I hope know it is clear to all.You can also Google it and know other facts about Kolkata metro. Thanks...

Hello, This post is for kids studying in 8th std.I say 8th so that you may know this right from this stage.Actually boiling occurs when atmospheric pressure is equal to vapour pressure of water.This means if atmospheric pressure is in equilibrium with vapour pressure.You will know about vapour pressure in 11th std.For now know about atmospheric pressure.It is the pressure applied by atmospheric air on surface of water.As atmospheric pressure is not always same so boiling point will also change.At high altitudes atmospheric pressure is lower so boiling point is nearly 80 deg Celsius at a height of 8000ft.Thats why food is not cooked properly at high altitudes.Now you have known the real reason of boiling. Thanks...

Hey guys, This post is for engineering students.If you are in the first year of engineering then let me tell you that 2+2 can  be 4 or may not be.This is a metaphor meaning 2+2 can be 3.9 or 4.1 but may not be equal to 4.See if you are pursuing mechanical,civil or electrical then your answers may not match the desired value but approximately around it.For eg if you are calculating the tension in a spring caused by a block of wood of 5kg,theoritically the tension should be 49 N under ideal condition.But we know that engineering is not about ideal,it is about practical.So you may get values as 47.5 or 48.Dont worry you have performed the right experiment.But can we always take it for granted that we should not care about exact value.The answer is no.You should always strive for perfection.Suppose you are a civil engineer building a bridge and you are neglecting the difference between required value and achieved value at every support then you may end up with disastrous results.So y...

Hey guys, You must have heard that you should keep your phones switched off or in aeroplane mode while traveling by plane.Actually the reason behind this is that the radio waves generated from your phone can really interfere with the electronic systems of plane which also depend on radio waves for their functioning.By keeping the phone in aeroplane mode all the wireless signals are turned off.Second reason is that if you use your phones at a high altitude from ground it would attract multiple signals from ground thus increasing the traffic which would disturb the signals at ground level.Third reason is that the federal aviation authority keeps it mandatory to keep phones turned off during flight.So I hope you now get a little insight about this fact. Thanks...

He he, Since the topic can appear to be funny so I welcomed you all this way.Actually the question is not funny because it is obvious for us to think that why can't we use any other fuel than petrol.The answer is yes you can drive your car to a certain distance in emergency by putting vegetable oil in the tanker but it will create noise and improper combustion will occur leading to detonation and knocking.This is because your Car's engine is not designed that way.It will deteriorate your engine's life in the long run.But yes for experiment purpose you can give it a try definitely. Thanks...

Hii, This post is very special to me as I thought about this in 11th standard while reading my physics book.You will ask how it is related to physics.Well I am going to corelate the above question with physics.We all know that when a number is divided by smaller numbers the result is a big number and it tends to infinity when the denominator comes closer to zero.Okay now how can we relate this to physics.You all have heard about black holes.But do you know how they are formed.When a gigantic star comes to its end it shrinks into the space time fabric with its mass remaining same.As a result it gets penetrated in space time fabric and no one knows what happens henceforth.Similarly anything divided by zero is undifined and while solving it the whole number line will collapse to a point.This is the reason why I believe that black holes also get converged to a point that is the point of singularity.Hence for mathematics anything divided by zero is undefined. Thanks....

Welcome back guys, The above question must have been asked to you at least once in your life by your elderly teachers or friends.If not I am asking you today.Actually the answer lies in the fact that whether you are weighing them in presence of air or in vacuum.If measured in air the weight of cotton would be felt less due to the upthrust of air on it,giving  it bit of floating effect.But in vacuum both will weigh the same. Thanks...

Hey guys, Power cut is always disturbing.Sometimes you miss your favourite TV show sometimes you lose touch from reading anything and so on.Specially during summers you can't tolerate power cut for long.To address this issue engineers created inverter.Now we have heard about sine wave inverter which work on sinusoidal curve of current and time.And this is mostly used in our household.Next kind of inverter which very few of us have heard about is box-wave inverter or square wave inverter.Actually this was the first kind of invertor invented and mostly used for big machines in plants.The main reason why it is not used in our house is that it is quite noisy bcz current stays stable for a particular time before coming to zero thus generating a square in the graph.Whereas sine wave invertors are smoother and not noisy.I hope you got to know something interesting today. Thanks...

Hey guys, It's winter time in the Indian sub continent now and you all must be enjoying this winter.You all must have noticed that during winters the barking of dogs can be herd who are far away from us as compared to other seasons.Well this is because of the fact that sound is a mechanical wave and requires medium to travel and since air is colder in winters,it is suitable for sound to travel at higher speed.This is because colder air has higher density than warm air and the more the density of air more will be the speed of sound passing through it. Thanks...

Hey guys, Tornados cause destruction in many parts of USA due to the mixing of dry and moist air.They are capable of destroying houses and cars.But do you know where is the impact maximum?Well tornado whirls with max angular velocity at the centre.As in the centre of tornado the radius is min as compared to other points of tornado it moves with max angular velocity.Since the linear velocity remains constant so by applying formula v=rw we see that w is inversely proportional to r.The lesser the r,the more will be w. Thanks...

Hii, This post is specifically for Mechanical engineering students studying power plant engineering.You must have a knowledge of boilers,turbines,condenser and feed pumps and of course cooling towers.But have you come across the term economizers.Well of course you would have.Now I will explain why it is used.Bassicaly it is an accessory and not main component but has a huge impact on the life of boilers.Well after condensation when the water is sent back to boiler via feed pump its temperature is considerably low as compared to boiling temperature so it is needed to send this water after giving it heat so that after entering boiler it does not take much time to be heated.Thus it is passed through economizer to increase its temp before entering boiler.This saves lot of fuel which would have been needed without economizer.So it is economical to use economizer.Now you must have got the point why it is called so.Another benefit of using economizer is that it prevents cracking of boiler w...

Hii, All the engineers out there who work in thermal power plants must have heard about this term.ESP is a device located at smoke stack or chimneys to collect dust particles before releasing the smoke to air.As the dust particles can be harmful for people when they inhale the smoke so all the modern day thermal power plants use electrostatic precipitator.It consists of two electrodes,positive and negative.The dust particles while passing through these electrodes get attracted towards negative side which are then attracted towards positive electrode.It acts as an filter to remove the dust particles. Thanks...

Hii, All the computer lovers out there you must be knowing this fact that RAM is volatile memory.If not then today you would know.See a computer having 4gb ram means that it can support a software program of size 4gb or less at a time and not more than that.It stores the memory of a particular program for the time it runs and not after it stops.Thus the name volatile.ROM on the other hand stores all the history of activities performed.Thus it is non volatile.Now it must be clear. Thanks...

Hello friends, You must be knowing that power plants generate high voltage of the range 11kv to 22kv.Well if you think it's high let me tell you that this voltage increases nearly 10 to 50 times at substations and even more at national grids from where it gets transmitted to longer distances.Now you must be wondering why do we need such high voltages when our household voltage is just 220 to 240 volts.Reason lies in this formula P=VI,where power being constant,I depends inversely on voltage.Higher the voltage lower will be current and H=IR2T meaning lower current means lower heat loss.Thus to avoid losses voltage is kept high during transmission and is brought to desires voltage by step down transformers. Thank You...

Hello physics lovers, All of you must have heard the word resonance once in high school physics books.If not then today you would know.Well we all know that any object having swinging motion will have a frequency associated with it.Not only swinging object but any sort of vibration or sound will have frequency.This means frequency can be Mechanical,accoustical etc.so frequency is nothing but number of oscillations made in a particular time,si unit Hertz.Now what happens is that when the external frequency applied on an object matches with natural frequency of that object it vibrates with maximum amplitude.It can be catastrophic in practical situations.This is the reason why a troop of army personnel having March on a bridge are said to walk abruptly without matching the March of other members.This is because if the frequency of the army personnel matches with the natural frequency of bridge it would collapse.You would be astonished to know while traveling if your heartbeat matches wi...

Hello frnds, Today's post is something interesting and it is based on the lecture that I attended in first year of engineering.So we know that in today's scenario there are multiple branches of engineering.But there will always be difference between core engineering and branches developed from these basic engineering streams.So the first core engineering was civil engineering.But why do we say 'civil'? Actually the reason behind this is that during colonial stage when European countries were invading different parts of world with their military,they required local people of invaded countries for construction purposes.As they wanted local people to be in this process so they named military engineering as civil engineering.These people were trained by British military engineers to construct bridges,dams,hospitals etc.Thus the name civil engineering came.After this came Mechanical and then electrical.After that all branches evolved from these branches. Thanks.

Hello friends, Have you ever wondered why mountaineers bleed from nose at high altitudes?See,as we move to higher altitudes the atmospheric pressure drops and due to this considerable pressure difference occurs between the flow of blood inside our body and outside.Therefore blood tends to come out from the possible holes in our body.Another reason associated with this phenomenon can be associated with the fact that at higher altitudes humidity is less which makes our skin dry leading to cracks through which blood comes out. Thanks...

Hii, We hear the term accuracy and precision almost every time during performing experiments of physics.But most of the time we think both are similar.Answer is no.An experiment is accurate if it matches with exact desired value but precision is getting similar values time and again but not the exact value.Let me give you one example,suppose you are performing an experiment to get the value of g(acceleration due to gravity) whose exact value is 9.8.Now while performing this experiment if value comes to be 9.8 it is accurate but if you record 3 values like 8.7,8.6,8.8 they are considered to be precise not accurate.Thus precision is about getting close values each time and accuracy is getting the exact value.I hope it is clear now. Thanks...

Hii, We all dream to board aeroplanes once in a life.For some it is scary and for others it is adventurous.Well flights are considered to be safest mode of travel.But mishap can occur any time.So there are many cases where accidents or air crash has occured.So black box is that machine which is small in size and kept at the back of planes to survive the damage. It remains intact even after crash.It records the communication between pilots and the communication which pilots make with air traffic control and every minute data of flight.From seconds from disaster it keeps the data of what pilots had to say before disaster.It is useful for air crash investigation. Although it is named as black box but it is orange in color.In aviation industry,it is known as flight recorder.So  I hope you got to know something interesting today. Thanks....

Hii, All the boys out there,shaving fascinates us.Isn't it.We all grow up  watching our father or elder brother doing shaving and wish for the day when we start shaving. Ok so while shaving when we dip the brush into water it starts shrinking.But have you wondered ever why does it happen?Well it's simple.It is due to the surface tension of water.The topmost surface of water gets pulled inwards as there is no water above it.Due to this reason tension is created on the brush towards inside leading to shrinkage.It is the same reason why rain drops get flattened after landing.Now I hope this phenomenon is clear. Thanks...

Hii, You must have seen once in your life on internet that there are several full forms given about computer.Dont believe them as there is no full form of computer.The word computer has emerged from the word 'compute' which means to calculate.There is no other full form of computer.Computers were invented to do big calculations.The origin of computer is believed to be developed in China from abacus.Then there were several generations of it.Initially the size of computer was about two big rooms which were mainly mechanically operated and vacuum tubes were used.After that transistors were used.Later on IC chips were used.We normally use 4th generation computers.5th generation being Artificial intelligence.As you are reading this now somewhere in the world more advanced technology is being developed.I hope now you would not be misguided about its full form. Thanks...

Hii, Many of us must have wondered once in a life that what causes aeroplanes to get lift.Basically it is based on Bernoulli's principle of energy conservation which states if kinetic energy increases,pressure energy has to decrease for the equation to stay true.Based on this principle the wings of planes are designed in such a manner that air passing over the wing moves at a higher velocity(ie higher KE) meaning pressure to be lower than the air passing beneath the blade.That is why an upthrust is caused leading to lift of plane.I hope now it's clear to everyone. Thanks...

Hii, You must have wondered whether alternating current is dangerous or direct current.Well most people would think that Ac is dangerous as all the big machines operate on this but answer is DC.Reason is simple,direct current is constant with change in time wheras alternating current changes its path from maximum to minimum and also being zero at a time.This is the time when it allows you to detach yourself from the source of current. Thanks..

Hii guys, As we know the frequency of our household current is 50Hz.But have you ever wondered how it is obtained.I will explain to you in this post.The turbines responsible for generating electricity in India are run at 3000 rpm,meaning 50 rotations per second.Hence 50 hz frequency.Similarly in usa turbines rotate at 3600 rpm meaning 60 rotations per second,hence 60hz.I hope now it's clear to you all. Thanks...

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Hii guys, Have you ever wondered whether voltage is directly proportional to current or current is directly proportional to voltage.Mathematically both are correct but conceptually current should be proportional to voltage.Because unless and until potential difference is there no current would flow. Thanks...

Hii, As we know that our universe started to grow in space time fabric and it's expanding.But have you ever wondered what is space time fabric all about.It is a dimension in which everything in the universe exists.It acts as a fabric meaning it can be depressed by the matter on it.Now you will think how it can absorb or get depressed.For that you need to know the concept of black hole.What is black hole?Whenever a gigantic star reaches to death,it shrinks to zero size keeping the mass same.This creates a hole in the space time fabric which consumes anything coming close to it.Had space time been not acting as fabric it would not have happened.so we can now have idea that how space time acts as fabric.Hope this blog is useful. Thanks...