Apple TVs Physical Review: A Surprisingly Dark Look at the 80s

Physics – Basic Introduction

in this video were going to cover some,basic concepts such as,displacement velocity acceleration,projectile motion,newtons three laws,forces momentum and things like that,so for those of you who want a basic,intro into physics and just want to,understand some principle ideas,involving physics this video is for you,so lets begin the first thing were,going to talk about is,distance,and,displacement,now many of you out there are very,familiar with the word distance,when you think of distance when you hear,the word distance what do you think of,i think of,how far,something has traveled,so lets say the distance between,one city to another could be a hundred,miles and so is the the difference,between,two points,now displacement is very similar to,distance but,displacement,encompasses direction as well,direction is important for displacement,so let me give an example that,distinguishes distance and displacement,so lets say if you have a person,lets say john,and hes at this position right here,and he decides to walk lets say,eight meters east,and then,he turns,in the other direction and travels,lets say,three meters,west,the total distance that john travels is,eight plus three or eleven meters,however his displacement,is not eleven but rather his,displacement,is five meters,displacement,is the difference between the final,position,and the initial position,so lets say if we have a number line,and lets say this is position zero,so john traveled,eight meters east,so now hes at position,eight on a number line,so during the first part of his trip his,displacement was positive eight,then he traveled,three meters,west,so his displacement is negative three,so now hes at position five,and so his,net displacement,is five meters because he started from,position a and now hes at position b,which is located at position five,and so your net displacement is,basically,its the final position lets say pf,minus the initial position,his final position is position five,his initial position is zero,so his displacement is positive five,he went from a to b,and so thats the basic idea behind,displacement,the total distance is 11.,now distance is a scalar quantity,it only has magnitude,displacement is a vector quantity,it has both magnitude and direction,in the case of distance,in the first part of the trip he,traveled a distance of positive eight in,the second part he traveled a distance,of positive three and so the total,distance is 11 meters,now displacement has the magnitude and,direction,during the first part of his trip,his displacement was positive eight,the magnitude is,how far he traveled which is eight,meters,the direction is hes traveling east,and so we have a positive sign for going,in an eastward direction,anytime you go towards the right youre,going in the positive x direction,so the displacement is positive,now during the second part of the trip,hes traveling west,that is towards the negative x direction,and so its negative 3 in terms of,displacement but in terms of distance,its positive 3. keep this in mind,distance is always positive but,displacement can be positive or negative,if youre traveling east,or north,displacement has a positive value,if youre traveling west or south,displacement has a negative,value and so if you add up the,displacement for the first part of the,trip,plus the displacement of the second part,you get the net displacement of positive,five,positive eight,plus negative three will give you,positive five,now lets say a car,travels,200 miles,would this description,be related to distance or displacement,so if i say you travel 200 miles,am i describing distance or displacement,well this would be a description of,distance,because no direction was indicated,so you could be going east west north or,south,if you simply state 200 miles youre,describing distance,now lets say if the car traveled 300,miles,north,in this case,i have the magnitude which is 300 miles,and i also have the direction,which is in the norfolk direction,so in this case im describing,displacement,displacement is a vector quantity,it has both magnitude,and direction,whereas a distance,is a scalar quantity,it only has magnitude such as 200 miles,without any direction,so make sure you understand the,difference between a scalar quantity and,a vector quantity,a scalar quantity as we said before,has magnitude only,but a vector quantity has a magnitude,and direction,now lets talk about speed,when you think of the word speed what do,you think of,speed tells you how fast something is,moving,so lets say if,a car is traveling 30 meters per second,what does that mean,so that means that every second,the car,will have traveled a distance of 30,meters,so lets say this is the starter line,and im going to use a box to represent,a car,and the car is moving in this direction,with a speed of 30 meters per second,so one second later,the car will have traveled a total,distance of 30 meters,two seconds later,its going to travel,another distance of 30 meters so for a,total distance of 60 meters,so we can make a table,so lets put,t for time,d for distance,so if the speed,is 30 meters per second,so every second,the distance traveled will increase by,30.,and so thats what speed tells us,it tells us how fast the distance,of an object or the distance traveled by,an object is changing every second,so lets say if youre driving a car and,youre going 60 miles per hour,every hour at that speed you will travel,a distance of 60 miles,so lets say if you want to travel a,distance,of 300 miles its gonna take you five,hours to do so,in the first hour youre gonna travel 60,miles,in the second hour you have covered a,distance of 120 miles,so every hour youre going to travel an,additional distance of 60 miles,now theres a formula that you need to,know,and its d is equal to vt,in this equation,d,can be used as a distance,and v,represents speed,t,represents time,now sometimes with this formula,you could use the velocity in terms of v,and if you do so then d,will no longer technically be,represented by distance but its going,to be represented by displacement,and so you could use that simple formula,in many different ways,so heres a question for you,so lets say if you have an object,that is moving,at a speed of lets say,50 meters per second,how long will it take,for this object to travel a distance,of 1000 meters,so were looking for the time how long,so we could use this formula d is equal,to vt,so the distance is a thousand meters,v is 50 meters per second,and we need to calculate the time,so we can divide both sides by 50.,and so its going to be a thousand,divided by 50. if we cancel a zero,thats a hundred divided by 5,which is 20. so its going to take 20,seconds,for this object to travel a distance,of a thousand meters,now lets talk about speed,and velocity,so what is the difference,between these two quantities,because they both describe how fast,something is moving,but theres a difference between them,speed,is a scalar quantity,and velocity,is a vector quantity,speed is always positive velocity can be,positive or negative,now recall that,a scalar quantity only has,magnitude,whereas a vector quantity,has magnitude and direction,so can you think of some examples,that will distinguish,speed from velocity,so lets say if a train,im going to use a box again,is moving,at,45 meters per second,let me take away the arrow,so i you dont have any direction its,simply moving at 45 meters per second,in this case,this describes the speed of the train,because im telling you how fast its,moving but not where its going,now lets say if we have a train,moving at 30 meters per second,going,west in this case this is a description,of velocity,because,not only do you have the magnitude of,the vector which is the speed,but you also have the direction,and so when you combine magnitude and,direction,you have a vector quantity and so,velocity,is basically,speed with direction the 30 meters per,second tells you the speed,wes tells you the direction,and wh

Physical Review tutorial for authors: How to write a great scientific paper

Jean-Michel Raimond and Cristina Marchetti – Co-Lead Editors of Physical Review X

absolutely delighted now to be joined by,Christina machete and John Michell Ramon,from physical review x first of all,welcome thank you very much indeed for,taking the time to talk to us I,appreciate that so lets kick off give,me a little bit of an insight a little,bit of an overview of you will on,physical review X what is it well let me,first of all say that you know birthday,Michelle and I are really excited and,honored to have the opportunity to serve,the community in these leadership role,and this is a fairly young journal as,you know it has been around only in five,years and actually in these five years,it has seen a remarkable brought in,state role and impact in the community,and this has really been due to the work,of the first lead editor which was,hardly pulling but also to really,amazingly dedicated work of the staff,editors that resided be at the APS,lesbians being really very impressive oh,yeah and and to present the John Allen,in a in a few key words its a,small-scale publication which typically,published 200 you are not 50 papers a,year but we dont aim to to grow that,much its for very influential very,pivotal papers in physics that we try to,identify for rather severe but,interactive selection process its and,it has no size limit which i think is,important because its only published,open access on the web so we dont need,paper and means that the offers can take,time to really explain their findings,which is particularly important all the,more so when the findings are really,knew how important is it that its open,access I think its pretty important of,course most institutions in the world in,physics institutions subscribe to the,APS Jonah so for the professional,physicist browse the differences,but first value very strong incentive,from the funding agencies to publish my,own mind open access journals and,certain epi X is the first step of the,APS two after that and then I think its,also important because as krishna,variety said we would like to attract,papers which ill beat out outside the,mainstream of physics with mesh,connections with other feet make,connections with our concepts and for,those who are interested in wisconsin,where might not have a subscription to a,PS at large and finally think its,important for students of the undergrad,students most probably we cannot in,access the aps for publications for an,institutional thing final question then,is whats your vision for the future of,the journal where do you want to take it,well firstly we want to continue you,know the kind of growth in in fact,invisibility the first dream very,quickly and as well in quality as a,matter of fact so we do not expect or,flying to make the journal a lot bigger,in term of number of papers published,and then it is now and we really expect,to try to maintain the you know the high,quality of the paper the other thing is,really important that we wish to,continue in spite of the increase of the,number of publication is this really,highly interactive and personalized,review mode that the journalists had the,editors actually have a lot of back and,forth with reviewers and with autos and,i think that has been very well accepted,and taken by it by the community oh,thank you very much for talking to us so,appreciate it thank you,you

A New Journal – Physical Review Applied