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at 15:59 sal said not all of it will evaporate only a little bit less than half of it will isn't it a little bit less than all of it will evaporate | -QpkmwIoMaY | A little under a liter will evaporate. There are two liters of liquid water to start with. It s a little bit less than half. |
At 7:25, Sal said three significant figures, but there was an edit that said he meant to say two significant figures. i thought 760 mm Hg had an infinite number of sig figs since it is a whole number. Am i wrong? and if so, could you explain why? | -QpkmwIoMaY | At one time, 1 atm as defined as exactly 760 mmHg. Thus the 760 had an infinite number of significant figures. Now, 1 atm is defined as 101 325.0 Pa or 101.3250 kPa. Also, 1 Torr = ¹/âââ atm. Historically, 1 Torr was meant to be exactly the same as 1 mm Hg. Subsequent redefinitions of the two units made them differ slightly (by less than 0.000 015 %). For all ordinary purposes, 1 atm = 760.0000 mm Hg (7 significant figures). |
At 9:05, why do they abbreviate mole? | -QpkmwIoMaY | Mole is very commonly abbreviated to mol. Dropping one letter isn t much, but it does help save space! We can t just abbreviate to m since that is already taken by meters. |
at 1:10 is mm Hg a form of pressure? | -QpkmwIoMaY | It is a way to measure pressure. |
What is the name of the original method used to portray the Cyclohexane molecule? 00:20 | YUEkOBvJSNg | if you mean before he draws it as tetrahedral then that s called its skeletal structure. |
Why at 3:22 the screen didnt move? or is it just my computer? | 7PgYb0c_3KE | Karl said that it was a picture |
0:37 it says below his hand stick n click but the title says click and stick why did he do that? | 7PgYb0c_3KE | I am not sure! |
Hello, at 5:53, how is the dimensional analysis working?
Why is Herz (oscillation per sec) times Js equal to just J?
Shouldn't we be left with oscillation times J??
What am I missing? | Zqt3btS1FwE | Oscillation isn t an actual unit. The units for Hz are 1/s so 1/s times Js gives you just J. |
At 5:00 David mentions Planck discovering this smallest, discrete amount of energy that light can deliver (6.626 x 10^-34 (J·s)). My question: how did Planck, in 1900 (!), quantify such a small quantity of energy? | Zqt3btS1FwE | He calculated it by making the hypothesis that energy comes only in discrete packets (i.e. the photon). He uses this assumption to calculate the frequency distribution of black body radiation with his constant h being the separation between allowed frequency values and it exactly matched what was experimentally observed. |
how come plancks constant is sooooo small? 5:43 | Zqt3btS1FwE | Planck s constant is the amount of energy a photon gains for each additional oscillation per second of frequency. That amount of energy is small. |
1:03 I still do not understand how can waves be localised? | Zqt3btS1FwE | They can t. That s why we say that photons are particles of light. There s an inherent irresolvable conflict between the wave view of light and the particle view. You ve put your finger on the most important aspect of the conflict: one of them can be localized and the other cannot. |
At 4:50 the energy of a photon equal to frequency times Plank's const.
How does the amplitude of the wave relate to this equation? The higher the wave the more energetic it is, isnât it? | Zqt3btS1FwE | Altering the amplitude of the wave will influence the intensity, which doesn t necessarily mean that there s more energy in the wave. We re talking photons here, via EM waves, so we don t relate amplitude to the energy of a light wave in the same way that we would for something else, like sound. We stick with E = hf, i.e. dependent on frequency only. |
3:37 So if light behaves as on or off, not in between, could there be a binary system based on light and whether not it's there? If so, could there be a computer based on the energy of a photon? | Zqt3btS1FwE | Your ideas are similar to those of a quantum computer. A photon can have pretty much any value energy actually, but when it interacts with bound systems such as an atom, then there will only be certain states allowed . I think this is what you mean by not in between . The quantum computer uses these not in-between states. And, rather than being a binary system, it has much more information per bit . keep up your thinking but do your homework too :) so that you have the info: your way of thinking is useful. |
At 6:00 pm, I want to clarify that if oxygen is having partial negative charge, it means that electrons are towards it but they are not in its valence subshell? | 126N4hox9YA | Correct. Oxygen has a partial negative charge because it is an electronegative element. It draws the electrons in the bond towards it, but they do not reside in oxygen s valence (If it did, it would be wholly negative). |
At 2:54, the video shows a bond of 2 carbon atoms, since they would have the same electronegativity you would consider it polar, even though there are 2 of the same atoms? | 126N4hox9YA | At 3:16 Jay states that this is a nonpolar covalent bond. |
In around 0:30, the lecturer drew a diagram of carbon and oxygen that I didn't really get. Can someone explain to me what it means? | 126N4hox9YA | He is comparing bonds between atoms to see if they are polar or non polar. This is a pretty big concept in chemistry. |
At 8:06, why was there 6 electrons surrounding chlorine? | 126N4hox9YA | because there are 6 valence electrons in chlorine s outermost shell or valence shell |
At 10:23 he says that sometimes you can consider a covalent bond to be an ionic one, but how can it be that subjective? Doesn't it have to be either covalent or ionic? | 126N4hox9YA | No, it doesn t have to be one or the other. Ionic bonding is really just polar covalent bonding taken to the extreme. |
at 10:51, if carbon gained an electron how does it have a negative formal charge? is it because the electron is negative? | 126N4hox9YA | Yes. In a neutral atom there are equal protons (+ve charged) and electrons (-ve charged). When carbon gains an electron, the number of electrons in the atom increases where the number of protons still remains the same. It creates an overall negative charge in the atom. * (carbon receives 2 electrons since it has 6 electrons and want two more to reach in stable condition) Hope it helps :) |
Around 5:15 it's explained that if the difference in electronegativity is less than 0.5 then it is a nonpolar covalent bond, and if it's greater than 0.5 it is a polar covalent bond. Well what if is exactly 0.5, what type of covalent bond is it most likely to be? | 126N4hox9YA | The numbers that Sal quotes are not universal, and will differ slightly depending on the source you check. In reality, all bonding is on a continuum, and the bigger the electronegativity difference, the more polar the bond. So, if the difference was 0.5 then you would have a covalent bond that was slightly polar. |
At 2:11, he says that carbon is partially positive while oxygen is partially negative. In another video explaining formal charge, he said to subtract the bonded electron amount from the valence electrons in the atom. For oxygen, this would be 6 valence - 6 bonded to it, giving 0. I don't understand why, using EN values it's negative, but using the way explained for formal charge it's 0. Is formal charge something different? | 126N4hox9YA | Oxygen is more electronegative than carbon. This means that it will attract electrons more than carbon in a covalent bond. Since electrons are slightly nearer to the oxygens than carbon then the oxygens will have a partially negative charge, which results in the carbon having a partial positive charge |
At 6:02 Jay states that the electronegativity of Oxygen is 3.5 and Hydrogen is 2.1 according to the Pauling Scale. Is there a way to figure out the Oxygen is more electronegative than Hydrogen without the Pauling Scale? | 126N4hox9YA | You can see where it lies in the periodic table and knowing the left-right top-bottom trends of electronegativity. Alternatively, you can extrapolate the fact that in water, the partial negative charge lies on oxygen to mean that oxygen is relatively more electronegative. (You can also calculate the exact electronegativity, which technically is without knowing the pauling scale values, it is irrelevant to what you are asking) |
At 5:58, Sal makes a covalent bond between oxygen and hydrogen, but is it possible? I mean Hydrogen only has one electron, and oxygen has six. Even with covalent bond, oxygen will only have 7 valence electrons. | 126N4hox9YA | There are other atoms at the ends of those dashes. He is showing you just the two bonded atoms. |
At around 6:50, could you not have used the fact that A is large (tending to â) v1= -vo/A = 0. Therefore, vI/R1= -vo/R2. Hence, vo/vI = -R2/R1. | U1KbM4ffiLg | Yes. Once you get the idea of how we are going to exploit the large value of A, you can go back through the equations and find places where you can make the simplification earlier. I carried on with the algebra a while longer until I got (1+A)/A. This is the point where making the simplification is a very strong clear argument, since it is so easy to see that this is close to 1. Once you grasp the idea, you should feel free to use it where you want. |
wouldn't it be the same if we take the assumption of the gain A to be large on the equation at the 6:50, and derive the same results,i.e. vout=-vin*R2/R1? | U1KbM4ffiLg | Yes, you can use the Large A assumption at any point in the derivation. |
At 6:35 , sal said at the Micro state is changing gazillion of a second but at last few minutes sal said "Micro state never changes , I don't get it , please tell me if I am missing something . | 5EU-y1VF7g4 | He means microstate is defined every instant, not that it doesn t change. On the other hand, we cannot talk about macrostate in every instant since it s not well defined. |
In 6:51 sal says that ALL macrostates stay the same after a second. Wouldn't pressure increase or decrease because new atoms are not touching or touching the walls of the wall? | 5EU-y1VF7g4 | I think, that a macrostate would stay the same only if the conditions weren t changed. So as long as nothing changes, all macrostates would stay the same. The pressure would probably generally stay the same because there s only so much area to bounce off of and so many molecules, so generally the pressure would be constant as long as no conditions changed that could lead to a fluctuation. |
In Sal's diagram at 11:22, the surface area of the block becomes half and the weight of the block becomes half, so should not the pressure remain the same? | 5EU-y1VF7g4 | Sal s intent was to erase half of the rock, but not half of the plate that the rock was resting on. The force is halved and the area remains constant, so the pressure is also halved. |
At 15:50, aren't the volume and the pressure supposed to be in different axis (switch between them)? The rock was shortened in half, yet the graph tells us that in the second state the volume got bigger? Maybe I didn't grasp the example very well. | 5EU-y1VF7g4 | the volume would nautrally increase because the the rock was haved and therefor the pressure exerted on the system would also reduce allowing the gas to expand to an extent thereby increasing its volume |
At 17:43 Sal says that macrostates are not well defined during the intermediate stage because they are continuously changing. But don't the microstates of the system change too? like we know that the gas molecules randomly move in any direction ,so their velocities are changing too. That's where we come across the concepts of R.M.S velocities,thermal velocities,isn't it? | 5EU-y1VF7g4 | Is your question if both the Macrostates and Microstates are not well defined during the intermediate stage? The answer to that is yes, they are both not well defined. When Sal said Macrostates he did not mean to make it seem like he was saying Microstates are not as well. |
At 11:44, why does the piston oscillates when the rock's mass is halved?
Thanks. :) | 5EU-y1VF7g4 | If you re asking why it goes through a bit of harmonic motion (oscillation), it s because the top has momentum after it is pushed up by the pressure of the gas so that when gravity takes over it is a little above the level that it reaches equilibrium. Then gravity brings it down and gives it momentum so that it is a little below the equilibrium level and the gas pressure takes over again. This process of oscillation continues until damping allows the piston to reach equilibrium. |
what sal had told at 2:56 , an ideal gas is always single atomic molecule gas? | 5EU-y1VF7g4 | An ideal gas is modelled as a monatomic gas. |
Why in 13:06 Sal says the system will get a lower pressure, higher volume and probably lower temperature ? I don't get the temperature part, temperature would remain the same, no? the system just decreases the pressure because it gains more volume, however KE and Velocity would be the same, but once the volume is greater the total force and change of momentum decreases, also decreasing Pressure. Decrease of temperature makes no sense. | 5EU-y1VF7g4 | The temperature could change, why not, the container that Sal uses was not specifically insulated through heat loss or gain to its surroundings. In any experiment of this sort, if temperature does change then the microstates of the molecules changes too, since temperature is essentially a measure of the heat energy of these states. To ensure that temperature does not change as you suggest you would have to keep the container at some fixed temperature, usually by immersion in a water-tank or some such means. |
At 3:09, what is a Balmer Rydberg equation? | Kv-hRvEOjuA | The Balmer-Rydberg equation or, more simply, the Rydberg equation is the equation used in the video. 1/λ = R(1/i² -1/j²) It is usually written as 1/λ = R(1/nâ² -1/nâ²), where nâ < nâ. For the Balmer series of lines ( the visible lines in the hydrogen spectrum), nâ = 2. So the Rydberg formula for the Balmer series of lines is 1/λ = R(1/4 - 1/nâ²). |
According to the diagram at 2:58, energy of photon from n=3 to n=2 is more than energy of photon from n=6 to n=5. Am I right? If right why is that so? | Kv-hRvEOjuA | Yes. Because the energy levels are proportional to 1/n^2. So they get closer together as n gets bigger. |
3:21 Jay says that the Rydberg constant is equal to 1.097x10^7/m but I've been told it's 2.18x10^-18J. Which one is right? Or are they the same, just with different units? | Kv-hRvEOjuA | They can t be the same thing with different units, right, because 1 J is not 1/m. The first number you have is the Rydberg constant. The second one is related, but not the same. It is the Rydberg unit of energy. It is equal to the largest energy transition that can take place in a hydrogen atom. |
At 1:00, does the emission of light connect to the emission of a photon? Are they the same thing? | Kv-hRvEOjuA | Yes, emitting light means emitting a photon (see my previous answer to your questions). A photon is a particle of light. |
At 7:50, he says that the glucose has a different way to get into the cells without insulin. What way do the cells use to get glucose. | 1JudNLK1-Ck | I think he said that because if there is insuline, glucose will be stock in muscules and liver in a polysaccharide form, the glycogen in animals. So, without insuline, glucose won t be stock in glycogen and there will be a lot of glucose in blood. This glucose with get in cells by some specific transporters, the glucose transporters also known as GLUT. |
Shouldn't be oxidizing water, not oxidizing oxygen at 16:26? | GR2GA7chA_c | Well, it s the oxygen in water that is oxidized, but you are right, it is not molecular oxygen. The idea is that the reduction of molecular oxygen to water is thermodynamically very favorable (that s why it s called oxidation) and that in the process of photosynthesis the reverse process is happening, which is remarkable. |
Around 00:35 he says that PGAL was the first end product of photosynthesis, but wouldn't the oxygen that was released through the light reactions be the first end product or am I wrong?? | GR2GA7chA_c | By product of photosynthesis, he is probably referring to an organic product created as a result of carbon fixation and that is used in the cell. With this definition, oxygen doesn t count, but you are absolutely correct that it is a product produced by reactions that are involved in the earliest part of photosynthesis. |
at 7:34 it says about lumeu,what is lumeu? | GR2GA7chA_c | It looks a bit like lumeu, but it is actually lumen. The lumen is the space enclosed by the thylakoid membrane. Protons are pumped into the lumen by the electron transport chain. |
at 11:56 what serves as the carbon source for photosynthesis | GR2GA7chA_c | The atmosphere and heterophs |
at 9:50, what happens if it is dark like it is going to rain, does the sun still go to to the plants??? | GR2GA7chA_c | Yes, sunlight does, but not as much and sometimes a lot less than on a sunny day since a lot of the visible light is blocked by the rain clouds. It gets dark like it s going to rain because there are lots of clouds in the sky, and of course it s these clouds that sometimes actually do rain on us. If these rain clouds blocked out all the light from the sun, then it would be as dark as night, which doesn t happen even on very cloudy days. |
At 13:18, why are the hydrogen protons attracted to the Stroma from the Lumen? Presumably the Stroma is more electropositive than the Lumen. What is happening here? | GR2GA7chA_c | There s a concentration difference. There are more hydrogen ions inside the thylakoid that outside, if I recall correctly. Because of the rules of diffusion, the ions flood out. |
at 12:28,what is atp | GR2GA7chA_c | ATP stands for adenosine tri phosphate. It is the energy currency of a cell. It is the form in which our cells generate energy from the food we eat. Hope this helps :) |
Where do the H+ in the stroma come from? (16:53 and other places) | GR2GA7chA_c | H+ are returned to the stroma during ATP synthesis - the Calvin cycle is a regulator of the H+ ions in the stroma (NADP picks up the H+ ions and used in the cycle). For it to first contain H+ ions, all that happens is the disassociation of water (H2O) into a hydrogen ion (H+) and a hydroxide ion (OH-). |
Around 8:50, Sal shows us the structure for Photosystem II. However, I was wondering if his numbering of these is arbitrary for the sake of differentiating multiple proteins, or if the numbers (I, II) signify different protein types? | GR2GA7chA_c | The two complexes are different but serve similar roles and so are numbered I & II rather than given completely different names. Which one is I and which is II is a result of the history of their discovery and does not correspond to their function or importance in any way. |
At 12:40 Sal says photophosphorylation but writes photophorylation. | GR2GA7chA_c | photophosphorylation is correct. |
At 6:59 Sal says 'Phosphobilipid Layer', whereas Wikipedia writes it as 'Phospholipid Bilayer'. Does it make any difference? Apologies if question has already been asked :) | GR2GA7chA_c | It does not make any difference. Both are acceptable. |
6:05
Why did he cut himself off so early? | GR2GA7chA_c | He wanted to stick to one topic.... He would probably waste time talking about that |
At 14:05, Sal says, "the electrons keep entering lower energy states." How does an electron enter a lower energy state? | GR2GA7chA_c | The electron loses energy when it goes down the electron transport chain because it needs to power the proton pump to create a concentration gradient so that the hydrogen ions can go through ATP Synthase and create energy. If you are asking about this for a class, you shouldn t need to know the specifics of how the electron loses energy because you are only expected to know the overall concept of what is happening. If it is just out of curiosity, I m sure you can find something on the internet about it. |
At around 3:00, he mentions that the chloroplasts appear green because they reflect green, and absorb all the other colors. Then why do some plants appear to to have colors other than green? | GR2GA7chA_c | Chlorophylls are green pigments in plants. Carotenoids are red to yellow pigments and transfer their energy absorbed from the sun to chlorophyll. There are other pigments as well, but they tend to be found in algae and kelp. |
How is oxidising oxygen equals to oxidising water? I don't understand what Sal said at 15:43 to 15:56. Could anyone clarify? | GR2GA7chA_c | The substance is oxidised by an oxygen atom, so it has gained oxygen. Oxygen oxidises other substances. |
At 14:30 Sal says photosystem I, but on the diagram it says photosystem II. Is it photosystem I or II at 14:30? | GR2GA7chA_c | I think it s photosystem II, Sal kind of corrects himself later in the video. hope this helps! |
At 6:17 Sal mentions that chloroplasts were once other organisms incorporated into the cell...does that mean genetic material in chloroplasts is different from plant DNA? | GR2GA7chA_c | Yes, the genetic material in chloroplasts has a different sequence from the genetic material in the nuclei of the plant. |
Around 9:30 or so, he says photons excite electrons in the photosystem II. What does he mean? | GR2GA7chA_c | It means the photons put the electrons in a higher energy state and their energy fuels the pumping of hydrogen protons into the lumen. |
At 1:08, I thought there are 3 stages of Photosynthesis- capturing energy from sun, converting energy to ATP and NADPH, and synthesizing them into carbs, and these 3 stages occur in 2 different processes- light dependent and light independent? | GR2GA7chA_c | Trapping energy from the sun and photo-oxidation of chlorophyll pigments, coupled with synthesis of ATP and NADPH happen during the light reaction. Synthesis of carbohydrates such as glucose and fructose happen during the dark reaction/calvin cycle. |
At 12:30 when Sal says this process is called photophosphorylation, does he mean the process of the H+'s going into the pump and creating ATP or does he mean when the H+'s go from the stroma to the lumen? or all of it? thanks | GR2GA7chA_c | I believe he is referring to the entire process. |
What do you mean by chemiosmosis? (at 13:12) | GR2GA7chA_c | Chemiostasis is where the energy stored in a hydrogen ion gradient is used to drive cellular work such as the synthesis of ATP. |
At 12:20, where does the ADP and the phosphate group come from? | GR2GA7chA_c | And they are recycled everytime a ATP is broken down in ADT and a phosphate group. (FUN FACT:Did you know that the A in ATP is the same base as the one found in your DNA? ATCG? and that in your DNA, ATP, TTP, GTP and CTP are used to form the DNA strand?) |
At 5:44 what is the little purple thing that Sal drew in the stroma. | GR2GA7chA_c | That s DNA. Chloroplasts have their own DNA. |
What does 'non-cyclic oxidative photophosphorylation' mean? (it is mentioned at 13:54.) | GR2GA7chA_c | Non-cyclic --> Not a cycle Oxidative photophosphorylation --> the synthesis of ATP through photophosphorylation (adding a phosphate group) of ADP **ADP becomes ATP |
Around 15:30 Sal talks about electrons being stripped from water. Do the Hydrogen protons move with their electron or are these two separated? | GR2GA7chA_c | Since water is H20, and one H is just a proton + an electron, then they go their separate ways, know its late but maybe helps :) |
Around 4:00, why would Y have a positive charge? | VymVIXcyErI | Y had a free pair of electrons and in the new configuration this free pair goes between the C and Y to form a double bond. Therefore there is less negative charge on the Y (because it is shared with the C now). Since the positive charge of the Y hasn t decreased, it becomes positively charged. I hope that explanation makes sense. |
At 1:49, I think that there is a third contributing resonance structure involved, with the positive charge localized (in LE theory terms, not in reality) on the carbon bonded to the oxygen atom. Right? | VymVIXcyErI | Since the structure you describe is used for simple ketones, I guess it must be valid here. I believe that it is a relatively minor contributor to the overall structure. |
(3:00) I think I'm a bit confused with electronegativity and conjugation. If Y is an electronegative atom, wouldn't it want to pull electrons towards it, not give them towards the bond with C to make a double bond? Thanks! | VymVIXcyErI | It does, this is why the k value is so large, the Y has very little propensity to give electrons to the double bond. He mentioned this structure because it still contributes to the molecules structure, just not much. |
At 7:20 , why is it that the red and white flowers produce a pink flower? Shouldn't the flower be either red or white? Since both of the "parent" flowers are hybrids, why aren't they pink, like their offspring, instead of red and white. | D5ymMYcLtv0 | In this case, he is talking about incomplete dominance. This means that the two alleles that determine color will cause a blending effect in the phenotype (In this example, it makes pink). The parent flowers would have pink as a phenotype, however the genotype of the parents are one red allele and one white allele, that, when combined, create a pink phenotype. |
At 1:05, there should be two sets of non-bonded electrons on the nitrogen in the sodamide anion. As drawn, it is a neutral radical. (Maybe I'm just not seeing the fourth non-bonded electron.) | HbDWBeRJboE | I think there is. It s fainter than the others, but wasn t there before. |
At 1:19, why is the halide opposite the reacting hydrogen the one that is eliminated rather then than the halide on the same side of the bond? | HbDWBeRJboE | This is an E2 elimination reaction. The H and the Br must be antiperiplanar to each other. This enables the developing p orbitals to overlap and form the Ï bonds. |
I was under the impression that Homologous Chromosomes had to do with synapsis during Prophase I of meiosis. At roughly time 8:00 Sal says that the chromosomes he was pointing to were "homologous." Wouldn't those two chromosomes be "sister chromatids"? | rV6O3rGulaY | Actually, he is pointing to two different chromosomes (at 7:30ish).Homologous chromosomes are two different versions (as in A vs. a) of a chromosome with the same function. These chromosomes that he is pointing to just haven t replicated themselves into sister chromatids yet. Sister chromatids are two identical copies of the same chromosome, linked at the centromere (middle portion) immediately after replication. They re shown as the X shapes in the next cell of the flowchart. |
At 2:27, Sal states that as x approaches c from the right, f of x approaches the same value it does as x approaches c from the left. I am confused about how this can be the case. It seems to me that the value of f of x as x approaches c from the right should be ever so slightly greater than the value of f of x as x approaches c from the left, as the value for which the function is undefined is between them - to approach the same value it seems you would have to "jump" over that undefined point... | 5i8HLmVTcRQ | You re right in that the value of f(x) as x approaches c from the right is ever so slightly greater than the value of f(x) as x approaches c from the left. If the difference between x and c (on both sides) approaches zero, f(x) will approach f(c), which is the definition of the limit. |
At 0:32, you said that states of consciousness range from alertness to sleep. What about anesthesia sleep? What about coma? Aren't they less aware than sleep? After all, in both of those states, pain does not cause awakening, right? Isn't that less aware? | WFnyLmL9t2I | Good question. The range of states of consciousness shown here could be seen as a subsection of the entire spectrum. Anesthetic sleep is a deeper than regular sleep, and a state of coma is even less aware than ordinary sleep. There are also states of consciousness more alert than every day awareness, for example during a rush of adrenaline. |
What about lucid dreaming? Is this what she means at 2:02? | WFnyLmL9t2I | She isn t really talking about lucid dreaming here, just the normal dream state. Lucid dreaming is a different state of consciousness than either awake or dreaming, because you are aware that you are dreaming yet you are still asleep. That awareness means that it is not a state of unconsciousness, it is something else. |
At 1:26, you say that people can induce daydreaming though light meditation, and at 1:51, you say people can induce drowsiness through deep meditation. What do you mean by that? | WFnyLmL9t2I | well i think it refer to your own training and skill in meditating, because meditating the first day is way different than doing it 3 months periodically. |
At 4:00 he says 1 cubic meter is 1000 L. Doesn't this depend on the density of the fluid? | dfZ9_vFwCA4 | Volume and density aren t the same thing. Density measures how much stuff occupies a specified volume. If the mass is greater for substance A compared to substance B, substance A will have larger density than substance B. This is because density is a ratio of mass to volume. However, both substances will occupy the SAME volume. |
I cant wrap my mind around newtons third law.. I exert a force on a block (on a frictionless surface) why does it move if it exerts an equal and opposite force? Is it because of the concept similar to what was stated about the earth and the star (i.e the difference in masses) (at 3:48)? Please be somewhat specific when explaining... | VfpKzwrhmqQ | Because the force it exerts on you is ON YOU, and the force you exert on it is ON IT. They don t offset. |
Near 5:00, he says the star stays put. I thought it moved ever so slightly in a relatively circular motion. | VfpKzwrhmqQ | Relative to what? Earth? Empty space? Please be specific. |
The third law states that for every action, there is an equal and opposite reaction. But in 0:55, it says that if the forces are equal and opposite they will cancel out. So does this mean that the third law is wrong or it is an incomplete explanation? | VfpKzwrhmqQ | Of course the third law is not wrong. Equal and opposite forces ON THE SAME OBJECT will cancel out , the net force on the object will be zero. Third law pairs are on different objects, not the same object, so they can t net to zero. I push on you and you push back just as hard on me. How many forces on you? One, not two. |
at around 7:10 you say it has to be equal and opposite always so what if you applied the force as fast as or faster than light? | VfpKzwrhmqQ | There is no speed to applying a force. Are you asking what happens if you apply a force to an object traveling at the speed of light? The Newtonian Laws are not accurate when you start dealing with velocities that are a large fraction of the speed of light. |
At 9:35, I don't understand what is the green force. What is that force? Where does it come from? Does it mean that the box is pulling the earth with somekind of gravitationnal field? Thanks | VfpKzwrhmqQ | It is the normal force. So, a box on a table does not accelerate through the table because there must be an equal force pushing the box upward as down (because the box is not accelerating or moving downward). The table is not actively pushing the box, but it is simply the force that prevents the box from further moving down |
Who Who Wait! At 4:29, massive object's gravitational should be greater!! How can a small planet exert that much force? How will one planet be closer to the star? Eg. Mercury is closer to the sun than the Earth? SOMEBODY HELP ME!! Physics is *CRUSHIN'* my mind. | VfpKzwrhmqQ | the planet s small (relative) mass makes it easier to accelerate which makes it so that even if the forces are the same the planet is the one that moves |
9:15 you said that the force on A (the box) is exerted by the B (the earth)
= F on A by B (downward)
the opposite would be
= F on B by A (upward)
10:55 you said that the force on A (the box) is exerted by the B (the table)
= F on A by B (upward) <--- this is wrong. i think this should be downward
opposite would be
= F on B by a (downward) <--- same as this, this should be upward
the box's weight is exerting the force downward, | VfpKzwrhmqQ | The weight is not a third law partner force to the contact force of the table. The weight is a partner to the gravitational field pulling on the box. Hope that solves it. |
At 5:11, the acceleration is going to be the net force divided by the mass, so will there be two accelerations with one net force? One for the star and one for the planet? | VfpKzwrhmqQ | Yes, the same force on different objects of course causes different accelerations for those objects, right? |
At 4:36 is the distance a factor of force? | VfpKzwrhmqQ | yes as force is a vector quantity |
in time 4:32 where can i find a SPDT for $0.05 ? | u5NCRHcel_g | You might have to buy a few hundred of them to get that price. Ebay is a good place to look for deals on bulk electronics parts. |
at 2:52 he got a positive answer, while at 4:21 he got a negative answer. Why is that? | CFSHq099Mx0 | No, he got the same answer at both; the slope is 0 which is neither positive nor negative. Let s call one point a and the second b. I will get exactly the same slope subtracting x and y at point a from the x and y at point b, as I will subtracting the x and y at point b from the x and y at point a, however the sign of the numerator AND DENOMINATOR of a-b will be exactly opposite that of b-a. Since they are exactly opposite, the sign of the quotient (numerator divided by denominator) will not change. |
At 2:35, I don't understand why -1 and -1 equals 0... | CFSHq099Mx0 | What Sal did: -1-(-1)=-1+1= -1 and 1 =0 What you said: -1 and -1 =-1+(-1)=-1-1=-2 I hope this helps you understand what Sal did! |
Sal said "one" but meant "negative one."
2:08 | CFSHq099Mx0 | That was corrected. |
At 1:00, the lines are parallel right? | CFSHq099Mx0 | yes the lines are parallel |
sal you make a mistake at 3:47 to have x2 not y2 | CFSHq099Mx0 | There is no error. Sal is just labeling the points so you can see which number will be (x1, y1) vs (x2, y2) . The points are correctly labeled. |
at 1:18, what do the triangles mean besides the y/x? | CFSHq099Mx0 | The triangles are the greek letter delta . It is commonly used in math to represent the words change in . So, triangle y / triangle x = delta y / delta x which is shorthand for: change in Y / change in X. |
@10:24 What is "back-filling"? | NYtPw0WiUCo | Sal s referring to the relative energy levels of the 4s and 3d orbitals. Intuitively, you might expect the orbitals to fill in the order 1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p, 4d, .... However, the 4s orbital is slightly lower energy than the 3d orbitals and the 4s orbital is filled before 3d. Hence, because the order is not quite what you expect, Sal referred to back-filling the 3d after filling the 4s. |
At 8:06 Sal says that Tin (Sn) has 4 valence electrons.
So you can write Tin (Sn) as: {Kr} 5s^2 4p^10 5p^2
But its highest energy electron is in p sub shell. So how is its valency 4? | NYtPw0WiUCo | The number of valence electrons is the number of electrons in the outermost shell s s and p subshell, not just the p subshell. There are two 5s electrons and two 5p electrons, for a total of 4 valence electrons. |
In 4:39, aren't all of the group two alkaline earth metals like beryllium and
magnesium reactive ? Helium is not reactive, so why put it there. Hydrogen is with the group one alkali metals because it's very reactive like other group one elements, but helium is very stable. | NYtPw0WiUCo | Helium IS a noble gas, BUT it has the same valence electron configuration as the other group 2 elements, eg ns^2 |
10:10
why is 4s^2 considered farther out, whereas 3d^6 is considered higher energy? i figured that 4 is the higher energy level? | NYtPw0WiUCo | the energy of orbital doesnot depend on the number beside the given orbitals but depend upon the number of degenerate orbitals the particular orbits have ie d shell has 5 degenerate orbital whereas s shell has only 2 degenerate orbital hence 3d6 has higher energy degeneracy means having same energy level |
At 9:25 why is Fe written out as 3d when it is in the 4th period? | NYtPw0WiUCo | Because the first row transition metals like iron are filling the 3d orbitals not the 4d orbitals. |
At 1:18, isn't helium part of the s' group electrons not the p' group electrons | NYtPw0WiUCo | Helium is a special case since it only has a single electron shell consisting of just an S orbital the second electron produces a completely full set of orbitals like the rest of the noble gasses. |
At 1:00 what do you mean by p block and s block? How do you know whats what? How do you fine this out,is there a special way? | NYtPw0WiUCo | if the electronic configuration ends with ns then its a s block element. if it ends with np then its a p lock element. but H is an exception |
at 5:00 in the video, he's talking about the electron configuration for Carbon, which is [He] 2s2 2p2 and so it therefore has four valence electrons. But how come we don't count [He] as 1s2 and have those two extra valence electrons? As in why Carbon doesn't have six valence electrons? | NYtPw0WiUCo | The valence electrons are the outermost electrons of an atom. Helium has two valence electrons. Carbon has only four valence electrons because the 1s electrons are inner electrons. |
At 9:30 Sal says that the furthest electron out is 4s2 but the electron with the highest energy is 3d6. But isn't the energy of the electron -13.6/n^2? n is bigger when the electron is more further out so if the electron is furthest out then because of the formula that electron should have the highest energy level. I am wrong? Or am i misunderstanding something? Also what is the reason why iron's reactivity is low? Sal says it's because of the superficial electron configuration but I can't understand. | NYtPw0WiUCo | You are trying to mix the Bohr model with the modern model. You can t do that. Bohr knew nothing about s, p, d, f. |