At the university, the dean and physics professor Sílvio Santos decided to implement the “roulette” evaluation method. Instead of taking written tests, students will have to spin a roulette wheel to get their grades in the subjects. This roulette wheel consists of a homogeneous disk of radius 100 cm that can rotate around a horizontal axis that passes through its center. The roulette wheel is divided into 10 equal parts, each corresponding to a grade that goes from 1 to 10, in ascending order, as shown in the figure below (no one gets a zero grade at UBF). To get their grade, students must spin the wheel and wait for it to stop. The grade that is next to the marker (arrow on the left) when the roulette stops will be the student's grade in the subject. The initial position of the roulette always corresponds to the note 10 (ten) being next to the marker, as in the figure, and the roulette only rotates counterclockwise.
Consider that you requested a transfer to UBF and went there to spin the wheel to try to pass in physics. You give the roulette an initial impulse so that it acquires an initial angular velocity ω0. The roulette wheel spins, making 8 turns and still advancing to note 5 where it then comes to a complete stop. Roulette starts and always stops right in the middle of each of the divisions. Assume that a constant clockwise angular acceleration α acts from the beginning of the movement until the roulette comes to a complete stop. The time the roulette was spinning was 216.3 seconds.
1. Under these conditions, calculate the angular velocity ω0 that you gave to the roulette at the beginning of the movement.
2. Now calculate the magnitude of the constant angular acceleration α that acts during the entire motion.
3. Calculate how long it took the roulette to turn the initial half of the total angular displacement.
4. Consider a point on the wheel that is halfway between the center and the edge. Calculate the value of the linear velocity of this point, for the instant of time 25 seconds after the start of the movement.
5. Consider a point on the wheel that is halfway between the center and the edge. Calculate the value of the linear acceleration resulting from this point, for the instant of time 25 seconds after the start of the motion.
6. One of the ways you rolled a 10 would be if you made the roulette wheel spin exactly 12 full turns. Calculate what value of initial angular velocity you should have given to the roulette wheel so that it stops after completing 12 turns. Use the same angular acceleration calculated in item 2 as it is the same roulette wheel. |
|
 Explain about "entropy"... |
Two objects, X and Y, are held at rest on a horizontal frictionless surface with a spring compressed between them. The mass of X is 2/5 times the mass of Y. The mass of X is 2/5th times the mass of Y. After the spring is released, the ratio of their respective speeds is Vx/Vy will be?
I know I have to use the formula m1v1=-m2v2 but after that I'm stuck |
421g of ice at 0 C melted how much heat needs to be added |
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is someone smart enough to solve this? i asked my brother ha cant help me...
An athlete throws the hammer at an angle of about 39.95 ° reaching the
distance of 86.74 m. The tool consists of a sphere weighing 7.26 kg and radius
0.06 cm and a chain and a handle for a total length of 1.195 m. The height from
from which the tool started was about 1.7 meters. The total turning radius is 1.95 m.
1. Calculate how fast the hammer was thrown
2. Calculate the angular speed of rotation of the athlete at the moment of the throw.
3. Calculate the centripetal force exerted by the athlete immediately before the release (assuming
a uniform circular motion and neglecting the force of gravity)
4. Write the trajectory equation and draw its graph. Calculate the coordinates of the
point of greatest height.
5. Assuming that once launched, the hammer rotates on itself at the angular speed of
0.2 rounds per second calculate the kinetic energy and potential energy at the point of maximum altitude.
Note: the moment of inertia of the hammer is 0.2 kg * m2 |
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If you're a contemporary from English-speaking countries who have started learning chemistry in your school, please let me know. I have also started learning chemistry (inorganic only) and I'd like to know how everything chemical is called in English. |
20847 - | | |   20944 - Reply from Emma173 , 9 yrs (Russia) - 2022-06-08
| | Hello. I am from Russia. Alabuga International school. We learn chemistry and science too. Currently we are learning properties of magnets. At tyhe lessons we make very interesting experiments. How are your lessons going? Please, share with me |
|
Hi am Solomon, I wish to know if there's some one who can help me calculate pressure in a U tube manometer |
20812 - | | | 20825 -   Reply from yangrunze8 , 15 yrs (China) - 2021-03-20
| | p=rho gh |
|
 It's too hard to study equations of physics like acceleration,gravitational acceleration....if u know any easy way or study trick let me know... |
20811 - | | | 20865 - Reply from Kyle123 , 16 yrs (Canada) - 2021-07-13
| | I don't think like that. Physics is the easiest among the all branches of science. It's so fun to study it. |
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If someone know how to become research scientist in sri lanka let me know...i already search but i do not know find any steps to be followed to become research scientist...what should i learn to become research scientist... |
20796 - | | | 20805 - Reply from Augustin220 , 14 yrs (France) - 2021-02-20
| | Hello, to become a researcher in Physical Sciences, you must have a Scientific Bac. Then, you must have at least a Master (Bac +5) in Physics, Chemistry. |
|
 Hi! My ambition is to become an Aerospace engineer.i'm choosing physics,Chemistry and combined mathematics as my A/L subjects. I just want to know how much of the periodic table you have to study. I mean it's not like all 118 elements are coming. I also wish to make friends with a girl who works in Caltehc. |
20745 - | | | 20750 - Reply from Mevindu135 , 20 yrs (Sri lanka) - 2021-01-20
| | You don't have to remember that.It's unnecessary work.It is given at the exam.And it is automatically remembered when you work for A/l.If you really need it,I have a short method.But it cannot be sent here because it is a picture. So tell me your father's or mother's email address.I'll send it to you. |
|
I like science because there are many experiments and about animals too. My father is physics teacher then I can learn science easily. There are science in physics too. I like science very much. |
 Im studying Chemistry,physics and biology for my advanced level exams.I can help you for chemistry or biology. I think im very good for those subjects.So anyone need a help feel free to contact me.I will treat you 100% respectful and kindness.Hope you guys are same. |
20685 - | | | 20749 - Reply from Mevindu135 (Sri lanka) - 2021-01-20
| | rmevindu@gmail.com |
|
20685 - | | | 20748 - Reply from Moses210 (Uganda) - 2021-01-13
| | Send me your email address for further inquiry |
|
I am having trouble with a problem on my summer work.
it is this:
A block of mass m is hanging by two strings of negligible mass as shown in the figure. String 1 is at an angle of 60∘ with the horizontal and string 2 at an angle of 45∘ with respect to the horizontal. Find the magnitude of the force of tension in strings 1 and 2. Express your answers in terms of m and g |
hello. I am Beara ，a senior High school student from China. I think chemistry and physics. I hope someone who good at that. can help me. please. My English is not very good ，and I think whenI ask u some questions I can practice my Rnglish. ，too. And I hope to know the student all over the world how you study. :)If u can.，I hoe u can send mail to me. And we can talk about studying，too. :D |
20583 - | | | 20684 - Reply from Mevindu135 (Sri lanka) - 2020-08-30
| | I can help you for chemistry |
|
20583 - | | | 20597 - Reply from Sanu245 (Sri Lanka) - 2020-03-27
| | Hi! I'm also searching for soeone who is interested in physics. We'll work together. |
|
Hello, I had my AP Chemistry midterm recently, and there was one question that seemed actually impossible. It probably isn't, and I wanted to see if any of you could solve it. (It seemed like it was impossible to combine the two last equations into the first.) This is the question.
Use Hess' Law to calculate the enthalpy of this reaction in kJ/mol:
4PCl3 => P4 + 6Cl2
Use these two equations and their respective enthalpies:
4PCl5 => P4 + 10Cl2 (1528 kJ/mol)
PCl3 + Cl2 => PCl5 (-111 kJ/mol) |
20561 - | | | 20683 - Reply from Mevindu135 (Sri lanka) - 2020-08-30
| | very easy. 1084 KJ/mol |
|
Hello everyone i search a man or a woman who has resolve the Riemann hypothesis because that very important !
:D |
20557 - | | | 20703 - Reply from Luna202 , 16 yrs (France) - 2020-10-14
| | Hi, if you found this person, then tell me how he did ! :D |
|
Please help me solve this question. An abrupt slowdown in concentrated traffic can travel as a pulse,termed a shock wave, along the line of cars, either downstream (in the traffic direction) or upstream, or it can be stationary. Figure 2-25 shows a uniformly spaced line of cars moving at speed v " 25.0 m/s toward a uniformly spaced line of slow cars moving at speed vs " 5.00 m/s. Assume that each faster car adds length L " 12.0 m (car length plus buffer zone) to the line of slow cars when it joins the line,and assume it slows abruptly at the last instant.(a) For what separation distance d between the faster cars does the shock wave remain stationary? If the separation is twice that amount, what are the (b) speed and (c) direction (upstream or downstream) of the shock wave? |
Here I'm ready for all questions
I like physics and Biology
If you have any questions ask to me
I'm a teacher of a school |
20411 - | | | 20558 - Reply from riemann64 , 100 yrs (germany) - 2019-11-24
| | hello could you help me how to resolve a bilan of energy with the equation of conservation ? |
|
20411 - | | | 20473 - Reply from Simeon205 , 13 yrs (Nigeria) - 2019-08-03
| | My name is simeon please can you help me solve this question. Compute your average velocity in the following two cases: (a) You walk 73.2 m at a speed of 1.22 m/s and then run 73.2 m at a speed of 3.05 m/s along a straight track.(b) You walk for 1.00 min at a speed of 1.22 m/s and then run for 1.00 min at 3.05 m/s along a straight track. |
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20411 - | | | 20433 - Reply from Julia64 , 13 yrs (Poland) - 2019-05-29
| | Hi Charles Reiss, how can I help you? I learn this one mounth ago, so I'll be happy learn you. |
|
20411 - | | | 20424 - Reply from Charles Reiss252 (England) - 2019-05-21
| | Hi there, can you please explain to which forms of energy can exist in |
|
 If anybody else loves since feel free to answer |
 Hey folks is there anyone else who loves physics too? Feel free to answer:) |
20392 - | | | 20786 - Reply from Zåû20 , 15 yrs (China) - 2021-02-05
| | Ilove physics!My dream major is closely connected to Physics and I'm working hard for it. |
|
 Hey there, I am rishabh and I am finding buddies to study chemistry. I know English because all my textbooks are in English. Thanks in advance.
Regards |
Hey everyone. i'm doing Chemistry in High school.Anyone interested in Chemistru feel free to talk to mr. |
20314 - | | | 20579 - Reply from Chetan Arya47 , 17 yrs (India) - 2020-02-23
| | I do care of ot.Maybe you can be my future assistant for DixTec.in. Hope to see you and some other guys there. |
|
20314 - | | | 20328 - Reply from Marek34 , 14 yrs (Netherlands) - 2018-12-03
| | Hey I'm also in high school and I love chemistry so when do you want to talk about it? |
|
Hi,
I'm currently studying Maths, Further Maths, Chemistry and Physics at A-Level! Anyone studying similar subjects or just has a genuine interest in STEM, don't be afraid to drop a message! :) |
20309 - | | | 20479 - Reply from Sandali135 , 17 yrs (Sri Lanka) - 2019-08-09
| | I'm also studying Physics and Chemistry and Biology. Actually they are very enthusiastic subjects. |
|
20309 - | | | 20360 - Reply from Sam181 (Germany) - 2019-01-30
| | Hey, I am interested. :) |
|
20309 - | | | 20358 - Reply from Anna57 , 20 yrs (China) - 2019-01-24
| Yes,I am a collage student to learn chemistry!!
But I cannot said it in English haaaaa |
|
20309 - | | | 20353 - Reply from Emina41 , 15 yrs (Zimbabwe) - 2019-01-17
| Hey
i'm interested in those subjects too |
|
I am just looking for people who love science and technology |
20239 - | | | 20421 - Reply from Nattcha12 , 22 yrs (Thailand) - 2019-05-10
| | Hello .. I'm interested in science too you can send me an email. If you want ...thanks |
|
SIENSE ISS FUNN ANND MAKS TINGS EXPLOD. |
Anyone interested in physics education? I'm going to Washington DC this summer for a conference about physics education research. (kind of nervous.....) |
 Does anyone want to be study buddies? I am doing a level CHEMISTRY and BIOLOGY and we could help eachother :) |
20199 - | | | 20292 - Reply from Sun155 (China) - 2018-09-22
| | Hello!You can call me Delis.I am an senior high school student in China.In fact I know a lot about Chemistry and Biology.I am glad to become your friend! |
|
20199 - | | | 20277 - Reply from Eric230 , 18 yrs (Spain) - 2018-08-27
| | Hey! I'm studying a Biochemistry university degree in Spain! We could talk if you want to! |
|
20199 - | | | 20263 - Reply from Marvin215 , 13 yrs (GHANA) - 2018-07-09
| | Marvin is my name.I'm 13 years old.I have hobbies. Such hobbies like;reading,painting and drawing,watching television etc. |
|
20199 - | | | 20255 - Reply from Kelvin173 , 28 yrs (Poland) - 2018-07-07
| Hello,
Kelvin here from Poland. We can be study buddies for sure. Kindly email me for more details and it will be worth it. I am an Informatics student in Poland. My email address prowrite247@gmail.com
Cheers |
|
 Hello, I am studying physics and would love to find people who are studying the same subject or are at least interested in physics. I will wait for your messages ;) |
20176 - | | | 20552 - Reply from aldo 187 , 21 yrs (mexico ) - 2019-11-12
| Hello, I study aeronautical engineering where physics is the most important thing I would like to talk to you about how physics looks in your countries and how they analyze it
greetings, I wait for your message |
|
20176 - | | | 20361 - Reply from Samantha181 (Germany) - 2019-01-30
| Hey, I want to study physics later on in my life but I always searched for someone to talk to about it.
We could learn together? |
|
20176 - | | | 20273 - Reply from ALI178 , 31 yrs (maroc) - 2018-08-23
| | I have a degree in physics and now I am preparing a new degree in Applied Math |
|
20176 - | | | 20238 - Reply from Martin178 , 19 yrs (Burkina faso) - 2018-06-16
| | I like physics and chemistry too.Tereby i study in physics field and i will love to be in touch with other physics fans |
|
20176 - | | | 20205 - Reply from Minfan83 , 31 yrs (Taiwan) - 2018-04-17
| | I love physics and the philosophy in it. (Relativity and Quantum Physics are amazing~) |
|
20176 - | | | 20180 - Reply from Omar46 , 17 yrs (iran) - 2018-02-15
| I am much intrested in Big Bang theory of the universe.
And yeah my field is math and physics with includes science in it to.
I'll be waiting to learn something from you or from someone else. |
|
20176 - | | | 20179 - Reply from Maelis233 , 16 yrs (France) - 2018-02-12
|  Hello ! :) I like physic too more precisely astronomy and the infinitesimal. What fields are you studying ? |
|
Comment maîtriser ce thème facilement ?? |
20158 - | | | 20258 - Reply from Magali94 (France) - 2018-07-07
| Salut pour maitriser le sujet qu'est l'éthanol. Il faut savoir pour commencer sa formule :CH3-CH2-OH. ensuite il faut savoir que c'est un liquide incolore, inflammable et miscible comme avec de l'eau par exemple. L’éthanol est un solvant tu peux le retrouver dans les produits cosmétiques. C'est un isomère de l'éther. L'éthanol peut-être créé industriellement ou naturellement (ex : la levure...)
J’espère avoir pu t'aider. ;) |
|
calculer le nombres de protoons et dedui en le nombre d electrons et de neutronsd ammoniac et merci beaucoup |
Hi everybody,I love to study scienice and math.almost everytime I study about them. And do not worry about english, I have book about science and math in english, so don't worry , I can talk or explain something about science and math in english fluently,if you want study with me it's okay or we can talk somethinge about it. |
20027 - | | | 20362 - Reply from Samantha181 (Germany) - 2019-01-30
| | Hey, I am interested in math and physics, maybe we could learn together or just talk about it? |
|
20027 - | | | 20108 - Reply from huanhuan97 , 18 yrs (Chian) - 2017-11-05
|  Hello, You are good at physics, and I want to learn physics with you in English. It is better for us to communicate with spoken english! |
|
20027 - | | | 20074 - Reply from Sarah233 , 12 yrs (Australia) - 2017-09-26
| | What year are you in? |
|
 I'm just looking for people who are interested in sceince and techology :D (it'd be perfect if you're interested in robotics, too) |
20003 - | | | 20078 - Reply from Allou Michel145 , 16 yrs (cote d ivoire) - 2017-10-04
| | slt les amis j'aimerai qu'on devient des portes |
|
20003 - | | | 20067 - Reply from Prisca158 , 13 yrs (France) - 2017-09-15
|  Bonjour je m'intéresse beaucoup aux sciences.
Cela me passionne depuis longtemps.
Si tu veux en discuter contacte moi en priver
PS: sait tu parler français, si oui répond moi en français. |
|
20003 - | | | 20041 - Reply from Vincent0 , 15 yrs (Kenya) - 2017-08-19
| | I've a problem with Albert Einstein's relativity theory |
|
20003 - | | | 20014 - Reply from Ishwarya151 , 18 yrs (India) - 2017-08-02
| Hey Irina. I have been wanting to find someone who shares my interest in robotics and artificial intelligence for forever now. So I feel like I can sleep more in peace at night after having 'kind of' met you(over dramatic, I know).
Hence here is to hoping we can build our friendship on our love for science and technology(robotics especially). Looking forward to talking to you!! |
|
Hi.
I really need help in balancing chemical equations. Also writing ionic equations in preparation ofsalts. I |
19983 - | | | 20114 - Reply from robin54 , 40 yrs (USA) - 2017-11-15
| | Please post your equation. Let's check if I can solve it. |
|
19983 - | | | 19985 - Reply from jackson26 , 17 yrs (tanzania) - 2017-06-25
| | bring your equation,(.......) eg.NaOH+HCl-NaCl+H2O |
|
 You want to know some simple things in Electromagnetism, you are welcome to ask me doubt, In theory and simple problems. I dont deal with relativity and I am an electronics engineer doing PhD. My area is ultrasonics. |
Hey,
I am 13 but really interested in chemistry and physics. Our chemistry classes are a bit slow for me so I tend to read ahead but when I came across the s,p,d and f orbitals I was a little puzzled. Right now we are learning about the periodic table and I was curious, when are the d orbitals filled? I read that in some cases the electron valence changes and was wondering under which circumstances the third shell can allow 18 electrons? I will be very grateful for any kind of help :) |
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19892 - | | | 19904 - Reply from Maria211 , 25 yrs (Venezuela) - 2017-03-29
| Now, when can a metallic atom host 18 electrons? When it forms "coordinated" bonds with "ligands". These bonds are a different type of bond. They aren't covalent or ionic. It's a way of sharing electrons through the "d" orbitals of the metals, that is, the metal "accept" the electrons of the ligand, forming "complexes". These complexes can have certain geometrical structures, that depend of the metal and the ligands nature. So, sometimes, they form complexes in with the metal has a total of 18 electros (counting it's s and p electrons).
Good luck! |
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