grayfalcon89

I'm in first year of physics in my high school but I really don't get this concept. Say I'm on scale and going up on the elevator with a positive acceleration. Then my force is F = m(a+g) But my teacher told me that it's different if the elevator is goin' up and slowin' down or if the elevator is goin' down and speedin' up. I do not get those differences in terms of Force. Can anyone explain it? Example will be nice. Thnx!

Well, I know THAT... Mass number = # of protons + # of neutrons, and I also know that it's the average of isotopes. I know ALL that. But you haven't helped my question yet.. I searched for Google , and only 100% sure thing I found was that atomic mass= mass number if the atomic mass is an integer. However, what about all the other cases where the atomic mass is not an integer? Round up to find mass number?

Hi, How do you find the mass number of element? Internet search told me that if I round the atomic weight, I get the mass number. I never heard of anything like this before so can anyone confirm this? Thanks.

Thank you! Yeah, I need to get better physics teacher.. arggg

I have two ambiguous questions that I could not understand from my worksheet other day in physics class. I was wondering if my answers were right so please help me. (I do not remember exact wording) 1. I'm traveling south with my boat 3 m/s relative to the river. The river's flowing east 2 m/s relative to the shore. Then my vector relative to the shore will a) slightly decrease b) slightly increase c) no change I put B because I thought that, "Hey, this sounds like Pythagorean Relationship" but I'm not sure. 2. When adding vectors, the length and direction of each vector must be a) similar to the that of resultant vector b) not changed c) reversed I put B because I thought that vectors can be shifted around AS LONG AS their displacement was same. A sounds like plausible answer though.

haha good idea... Thanks a lot guys. This has probably been most helpful science thread EVER! I and my partner (she did a lot of work) made tower that was 105cm. Record in our class was around 150cm.

Thanks for the help... Except... I still can't build tower and it's driving me nuts. I found out that today that the amount of tape is 30 cm and I have 43 minutes to construct the tower (well me and my partner). I've tried many methods given by here. Here are ones that I did: 1. Simple equally lengthed "tubes" tower... Didn't stand very far 2. Using some sort of cylinderlike (not very tall) base... Better than first one but still weak 3. Using three tubes to make a "tripod-like" figure as base (isn't that what you guys mean by triangle????)... Somewhat better but still weak I don't honestly understand what V or W mean... Can you guys like... make a picture or describe more? This is my FIRST lab and I don't want to get zero because I couldn't make a stupid tower.. arrr Oh by the way, I'm doin' this Friday so yeah.. not much time..

Hi, This is my FIRST year taking physics in high school (I'm senior) and our first lab which we get to work in class is building paper tower. I'm given one paper (about 28 cm x 21.5 cm; regular A4 paper) and limited amount of tape (I do not know exact but it's not "that" much) and scissors. I'm supposed to build a tower that's 1m high and standing. I've tried many methods and still am trying. But I'm stuck mainly of two reasons: 1. I can't build a solid base 2. I can't roll papers into same sized tubes (Yeah, it's not easy rolling papers... :-X). Help is greatly appreciated!

So, to put in simple term, shock is condition such that some parts of body do not get enough blood? We learned further about the shock on last class and here are 8 types of shock, which didn't include my initial idea of "electric" shock: Anaphylactic (life-threatening allergic reaction to a substance from insect sting or foods/medications) Cardiogenic (heart failure that results from cardiac arrest or heart attack) Hemorrhagic (already explained above i think... losing lots of blood) Metabolic (Loss of body fluids from vomiting or diarrhea) Neurogenic (failure of nervous system to control size of blood vessel) Psychogenic (emotional stress) Respiratory (failure of lungs) Septic (poison infection) My Q, now that I typed these, is why septic reaction is not included as subpart of anaphylactic? I mean... you can see these people who have allergic to bee sting, and doesn't bee sting similar to poison (in some sense)?

Hi, I've recently came across term "shock" in my Emergency Responder class. In the textbook by American Red Cross, the book defines "shock" as body's failure to some sort of event. I thought "shock" meant like electric shock that hospital people do to resuscitate hearts? Can anyone clarify on this term? Thank you.

I can't seem to find what these explanations refer to in my book. I tried internet but it doesn't help either so I'm asking help here. _ _ _ _ _ _ _ _ _ ---> A fused group of cells _ _ _ _ _ _ _ _ _ _ ---> Muscles that work in concert This was in muscle worksheet but way I view it, I don't even know if first one is term in muscle (if it is, maybe I don't know it?). Also, second one made no sense to me. Muscles that work in concert? Is there any other concert that rock 'n' roll concert? Thanks. I appreciate this. It would be great if I can get reply soon.

This was in our review for test Friday, and well, I don't quite understand what my teacher's answer was. Q: Why is it important to eat foods that contain water-soluble vitamins every day? He said: Excess vitamins get out of body by urine, and you need to refill them (?). Is that right? How? I thought that you needed to have "water-soluble" ONLY because large percent of body is water (didn't really understand why you need to consider "excess" part; I thought "excess" occurred if you took more vitamins than required in tablet ).

I'm writing up a critique for my chemistry class and at the end paragraph, I have to conclude with my point of view (early in the paper, I talked about the pros of the article and cons of the article by using evidences from the paper). What type of things should I address in the conclusion? I don't want to just bluntly says, "I agree(disagree) with...." and just end it there. What kind of things do you guys normally address at the end of critique? I'm putting this under chemistry because it's from chemistry class and deals with radioactive burial under the sea.

I'm junor taking AP Calc AB. I scored 80 on my PSAT junior this year and 70 last year. I think this is not more about what math level you are but how careful you are. Math on PSAT/SAT has very harsh curve so it's important that you answer them carefully and UNDERSTAND what question's asking. For instance, this is type of popular question: If x+3 = 27+2x, find 3x: Some people might put -24 because x = -24, and it WILL be one of the choices. WRONG! You're looking for 3x so it's -72.

I hope there is at least one person here who did this lab in their college. Well my class did this in our advanced biology class this week (i'm in high school) but search in google tells me that college people do so as well. Anyway, the lab is about leaf disc buoyancy which is basically by taking spinach leaf discs (you just take a straw and make small holes on it), vacuum out the oxygen so that they sink in the water, and then put them on water under photosynthetic lights and measure how many of them come up to float on the surface again. Other leaves are OK but we used spinach and I think all leaves (as long as they're not hairy) are OK. But here's my Q (sorry for long intro and explanation of lab): I and my partner added pH buffer 8 to one of our cups and this increased the buoyancy speed greatly. The question is, I don't know how it happened. So, I looked at the ingredient of pH buffer: Sodium phosphate Dibasic CAS No. 7558-79-4 Pot. Phosphate, Monobasic CAS No.7778-77-0 Searching google tells me that sodium phosphate can increase the rate of photosynthesis. http://biae.clemson.edu/biolab/PHSdisk.html But again, this site didn't tell me how it happened so that's why I"m asking here for help... Thank you very much!

Can't you just brute-force? After putting some numbers, it should be come apparent that one side is larger than other one. x^2 = 2^x x = 1 --> 1 < 2 x = 2 --> 4 = 4 x = 3 --> 9 > 8 x = 4 --> 16 = 16 x = 5 --> 25 < 32 x = 6 --> 36 < 64 x = 7 --> 49 < 128 Pretty evident..

I don't visit here often so sorry for late response. I use Internet Explorer.

What? I don't understand what you mean for #2. As for #3, that was my initial size (it would be too fat to go through). I'm not sure which one's really true though. It sounds (from the site) that they are independent and just are floating around the water. But I learned from the school that they form ionic bond so it's more than just "floating around." Now I'm honestly confused.. Is it size or hydrophilic/hydrophobic? By the way, since you didn't comment, I take #1 is right..?

Hey guys. I'm re-learning about osmosis in the school and I received this paper to answer. You can say I'm asking for homework answer but really, I can still get full credit by saying something "scientific" (the teacher doesn't check this ardently). But I really would like to know what's the right answer so I'm posting here. 1. When plant cells lose sufficient water, the internal pressure of the cell membrane pressing against the cell wall is (reduced, increased) and they (lose, gain) turgor pressure. My answer: reduced and lose. My explanation (this is unnecessary but here's why I think is): I know that in plant cells, cell walls restrict expansion by creating more turgor pressures. So, if the water decreases (which will be "shrinking"), the plant cells will lose turgor pressure and the internal pressure will decrease as a result. 2. The cells observed in tap water probably were at osmotic equilibrium; however, they were not immersed in an isotonic solution. Reconcile these two statements. My answer: Both osmotic equilibrium and isotonic solution are similar in a way that there both exist equal amount of solute concentrations in both sides of the cell. But in an isotonic solution, the amount of solute concentrations is always same. In osmotic equilibrium, there is constant movements of molecules moving back and forth to have same amount of concentrations on both sides but there is no "net" change in concentration. Because of cell walls, the plant cells in tap water can do going back and forth movements without expanding, and it is doing this because the tap water is hypotonic (not isotonic). 3. When salt molecules are dissolved by water, sodium and chloride ions are formed. They then become surrounded by water molecules. How does this relate to the fact that neither ion can pass through the cell membrane? My answer: This relates to the fact that the cell membrane is hydrophilic at the head and hydrophobic at the tail. When sodium and chloride ions dissolve in water, they become surrounded by water, and thus, become part of water molecule. So, they'll go through the head of cell membrane which likes the head but won't be able to pass through because the tails do not like water molecules. I hope these are right. I had to use internet to find answers (I have really bad biology book from school; there isn't much detail!!). If I'm wrong, please tell me. I'll appreciate greatly. If I'm correct, still tell me so I know I'm doing it right.

Thanks. That helped me a lot. yourdadonapogos, you're right. This does sound a lot like homework because it was from chapter exam review paper. However, it was just one of those papers that our teacher updated on the site and it wasn't homework ---- it could've been but he didn't assign it and I just did it voluntarily.

It shows up in this page too but then it disapears. And when I clicked on that page, I can see x^2 at the left top corner (although pretty small?).

1. The information needed by a pancreas cell to make insulin is stored in its cells molecules of _______. 2. Why should we limit the amounts of saturated and hydrogenated fats in our diets?

Hi, My school recently hired a new gifted teacher and well, she wants people in gifted club to do something as "individual project." I'm pretty busy but I want to do something that deals with medicine since that's where I plan to go. What would be a good project that is not TOO MUCH time consuming? I have to take SAT and other extracurriculum activities as well. Thank you! P.S. If anyone recommends job shadowing, that's my senior project so that's not allowed.

For odd reason, the Latex in this forum doesn't show up to me. It shows up as an image with "x" as "not displayed." I can still read the code if I put my mouse over it but I'm not sure what happened. Is there something in my setting that I have to do or..?

I came across types of two flows in my advanced biology book today. It's part of the concepts in exam but our teacher really didn't go over it so I'm asking here to see if I understood it. Two flows are the flow of chemical nutrients and the flow of energy within an ecosystem. Flow of chemical nutrients are like oxygen, water, and carbon oxide while flow of energy is basically "energy." The difference between those two is that while flow of chemical nutrients is constantly going on as "cycle," the flow of energy doesn't do that. Like say energy A goes into the ecosystem. It starts from plants to the animals and after animals used it, it goes out of ecosystem with energy B coming out simultaneously. Is this right? I'm not sure about the flow of energy part even though this is something similar (I think) what the book said. Thanks.