What is Clock: Definition and 483 Discussions

CLOCK (Circadian Locomotor Output Cycles Kaput) or Clock is a gene encoding a basic helix-loop-helix-PAS transcription factor that is believed to affect both the persistence and period of circadian rhythms.
Research shows that the CLOCK gene plays a major role as an activator of downstream elements in the pathway critical to the generation of circadian rhythms.

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  1. C

    Cannot solve Problems related to a Clock

    "A clock has an hour hand that is 15.0 cm long, a minute hand that is 20.0 cm long, a secondhand that is 25.0 cm long." "The time is 3 h 27 min 49 s" "the hands are moving clockwise" "for the hour hand calculate 1. speed of the hand 2. velocity of the hand at the given time" "presume the hand...
  2. M

    Around the Earth Clock: Does Special Relativity Hold True?

    Hi all I just started doing some research on special relativity and I figured something. If two people both reset their watches. One person goes around the Earth once, doesn't matter at what speed, and the other person stays there. The watch of the person that went around the Earth will run...
  3. D

    Is the Light Clock Calibration the Key to Understanding Relativity?

    Hello PF. Re. the light clock / train thought experiment. It seems to me that the clock calibration chosen, ( light's mirror to mirror path ), is determining the outcome of the experiment. And that a different calibration would give a different result. e.g. assuming the mirrors are one metre...
  4. ORF

    Has a real clock corrections, with respect to an ideal clock?

    Hello In Special (and General) Relativity, has a physical (real) clock corrections, with respect to an ideal (mathematical) clock? For example, the physical clock has mass, so it will affect its own measure. This is only an example I thought, I don't know if there are more corrections...
  5. D

    Tower Clock Gearing and Motor Speed

    Hello all, first post on here. My fathers friend recently died of cancer and he was the person we used to turn to for this question, I've been racking my brain and searching the net for info, found this link (http://www.schsm.org/html/gear_ratio_calculations.html) and have got the ratio down...
  6. V

    Does cosmic time (or comoving clock) run at the same pace at all times?

    My question is if the pace of cosmic time changes over time or not. I think this is identical to asking if the rate of a comoving clock changes over time. The FRW metric holds at any time, but only the spatial part expands: ds2=c2dt2-a(t)2dx2 Apparently, there is no time delation in the...
  7. C

    Solving the Horizontal Light Clock Puzzle: Length Contraction & Frame Shifting

    Consider a Horizontal light clock of length ##L_0## lying at rest in a frame K. There are two important events: (A) a photon gets emitted from the left mirror and (B) it gets reflected at the right mirror. Another frame K' is moving by at velocity v and the frames are in standard configuration...
  8. A

    Light clock - Galilean transformations

    We have two parallel mirrors, which are located at y=0 and y=l in the (x,y) plane. A photon is traveling between the mirrors, up and down along the y-axis. Consider an observer O at rest w.r.t. the mirrors. What's the time (Δt) measure by O for the photon to make a full period. Consider an...
  9. T

    Viewing a (giant) clock at relativistic speed

    Can anyone answer this question? What you would see while watching a stationary clock that you are moving directly away from at a constant relativistic velocity? Yes, any practical clock would immediately shrink to a tiny point an instant after you passed it. So, either assume a really huge...
  10. H

    Questions on length contraction in train light clock experiment?

    Hi guys, I've been thinking about this experiment for the last few hours and I have a few questions which I am deeply confused about. 1) In the light clock experiment, where light clock is set up so that light travels vertically, and the train carrying the clock travels horizontally, wouldn't...
  11. m4r35n357

    Time Shown on Clock Face of Moving Observer: Raytracing in Relativistic Flight

    I would appreciate it if some senior member would give me feedback about this result that I have been using in my raytracing simulations of relativistic flight, https://www.youtube.com/playlist?list=PLvGnzGhIWTGR8QYYvMCweXPHtZPnsjrw8. For simplicity I am assuming that the primed and unprimed...
  12. R

    A clock tower puzzle in a gravitational field

    In General Relativity spacetime is described by a metric. The most common one is the Schwarzschild metric, valid at radii greater than the surface radius of a mass. If we assume constant angular position so that dθ=dø=0, then this metric relates local (proper) coordinate time and distance dτ...
  13. D

    Need help understanding Einstein's Light Clock experiment

    A general summary of the experiment is that when the light clock is stationary on the platform it runs as normal, up and down, but when someone is looking at a clock on a moving train, it appears to move slower because the light has further to travel, and thus, time runs slower. What confuses me...
  14. M

    Is there a way to turn on/off the flow of water on this water clocK?

    Homework Statement The water clock in question is this: I currently have to build a timer for my high school physics class. I plan on using a very similar design structure as shown in the video. However, I would like to know if there is a mechanism/modification I can do to this so that...
  15. M

    Is there a way to stop the flow of water on this water clock?

    The one in question: Hello, I currently have to build a timer for my high school physics class. I plan on using a very similar design structure as shown in the video. However, I would like to know if there is a mechanism/modification I can do to this so that I can stop/greatly reduce the...
  16. A

    Time Dilation: Exploring the Effects of Speed and Gravity on Time

    As far as I'm informed time slows down the lower the gravity and the faster we move. Let's say I go out in space with an analog clock and orbit the Earth. When I come back to Earth after, let's say, a week will my analog clock show different time from the clocks on the planet ?
  17. A

    Clock synchronization process

    This is basically a follow-up to some questions from a previous thread regarding Einstein synchronization and other methods. I don't understand the alternative methods when the synchronization parameter isn't 1/2 and its connection to the speed of light. Basically it means that the light is...
  18. N

    Engineering Multiphase clock generator circuit and control logic

    I want to design a multiphase clock generator circuit and control logic. The circuit will have a 250 MHz clock and the circuit will generate three non-overlapping clock phrases running at 50 MHz. Each clock phase has an associated output driver that can drive up to a 10pF load with no more than...
  19. T

    Clock, calculate displacement, avg. velocity, avg. acceleration.

    Homework Statement A clock has a 20 cm minute hand. From the 6 PM mark to the 9 PM mark, for the tip of the minute hand, calculate: a. the displacement vector in unit-vector notation. b. the average velocity vector in unit-vector notation. c. the average acceleration vector in unit-vector...
  20. A

    Show the relative difference in clock time between plane/ground is

    Homework Statement http://puu.sh/7vC46.png http://puu.sh/7vBG5.png Note: In this image the ohm symbol represents the angular frequency of the Earth's rotation Homework Equations Gamma = 1/SQRT(1-v^2/c^2) V (relative to centre of earth) = angular frequency(R+h) +/- v v= plane velocity...
  21. R

    Track of the light in a moving light clock.

    There is a moving light clock at a certain velocity. For an outside observer, the light just seemed to be traveling in a slant path. So far, it is right for the outside observer, the light is going in a slant path and hitting the top bar and then again returning and hitting the bottom bar...
  22. B

    Understanding the Memory Hierarchy and Its Impact on CPU Performance

    I just was thinking somebody may be able to help me understand something about Computers. If I have a PC and the Memory in it is 1066 MHz I know the real Clock speed 533 MHz because DDR Dabbles the Data Rate. And if I have a CPU that is 2 GHz it is running at 2,000 MHz now this is what I...
  23. A

    Clock pulse 1 sec. long using flip-flops

    I was wondering how can i generate 1 sec. clock pulse using flip-flops?
  24. N

    How Does the Hour Hand's Velocity and Acceleration Change from Noon to 6pm?

    Homework Statement What are a) average velocity and b) average acceleration of the tip of the 2.4cm long hour hand clock in the interval from noon to 6pm. Use unit vector to express, wth the x-axis pointing towards 3 an y-axis towards noon. Homework Equations The Attempt at a...
  25. S

    Light Clock Confusion in Special Relativity

    When students are first introduced to special relativity, the first thing they are taught is the derivation of the gamma factor and time-dilation, and it goes something like this: Suppose there are 2 observers in space, let's call them Alice and Bob. Let's assume Alice is stationary from our...
  26. S

    LTSpice Clock signal distortion

    Hi I made a counter using Dflop in Ltspice. But when I am using the count bits as signal to other circuits the clock signal is getting distorted. Why is this happening? How can I overcome this problem? Thanks Salil
  27. H

    Clock of Observers: Who Sees Whose Clock Running Slower?

    We have three observers. The A is in earth,B is into a car that runs with big speed,C is out of galaxy. All observesr see that their clock runs normal. A will see that clock of B run slower,and B will see the same for A. 1) Logically, C will see A's and B's clock run slower from his...
  28. M

    Iodine Clock H2O2/I-/H+ why buffer it?

    The RSC Classic Chemistry Demos list the method for the hydrogen peroxide iodine clock variant as being buffered at pH5.8 with ethanoic acid/sodium ethanoate. Can anyone explain why it might be useful to buffer a clock reaction in this way? It seems this is for a demo rather than a serious...
  29. B

    MHB Algebra word problem: the angle between the hands of a clock

    1. What time between 2 and 3 o’clock will the angle between the hands of the clock be bisected by the line connecting the center of the clock and the 3 o’clock mark? can you rephrase for me the question. what's the unknown here? please help thanks!
  30. paulmdrdo1

    MHB Clock Word Problem: Solve in 2 Steps w/ Hints

    1. how soon after noon will the hands of the clock extend in opposite direction? 2. what time after 11 o'clock will the hands of the clock be at right angle for the 2nd time? can you please give hints on this, so i can start solving it. thanks! i have no idea where to start honestly that's why...
  31. K

    Figuring out Clock Desynchronization

    Hey, I can't seem to get my equations to work correctly to get the right numbers. I'm looking at the example here (A One Way Trip (Twin Paradox). In the lab frame (rest frame of the planets) I get this. Mars is separated by 100 light-seconds, and Bill travels at 0.8c. Therefore, Jim...
  32. S

    Find Displacement/ Velocity/ Acceleration of clock

    A clock has a 20cm minute hand. From the 6PM mark to the 10PM mark, for the tip of the minute hand, calculate: a) the displacement vector in unit-vector notation b) the average velocity vector in unit-vector notation c) the average acceleration vector in unit-vector notation d) calculate the...
  33. C

    How to define uniformly ticking clock defined in GR?

    I just read the following definition of a clock in GR: "A clock is a smooth embedding γ : t → γ(t) from a real interval into M such that the tangent vector \dot{γ} (t) is everywhere timelike with respect to g and future-pointing. This terminology is justified because we can interpret the...
  34. Y

    Why does the frequency of a light clock change when it is accelerated?

    This is an analysis of how a classic Einstein light clock behaves when accelerated orthogonal to its main axis. The results might be considered slightly controversial, so I am putting the details of the calculation here so that they can be checked.Consider a light clock that has its long axis...
  35. R

    Is the unsynchronised clock actually at the place where seen to be

    It all started when I read that different inertial observers from the same place at the same time should see same things. Say there are two clocks C1 and C2 in a stationary frame of reference S. C1 is at X=0 and C2 at X=X (some positive X) and both are syncronized in this frame. Say there is...
  36. C

    How to make LED display glow like a clock

    I machined my own 7-segment display out of clear polycarbonate, each segment is about 1.5" long (it's a rather large display) and now it's time to add the LEDs. Turns out that the usual LEDs with the epoxy lens focus the light too tightly on one spot, so I get more of a dot rather than...
  37. PsychonautQQ

    Can somebody walk me through this Special Relativity clock sync proble

    Homework Statement A rocket that has a proper length of 700m is moving to the right at a speed of .9c. It has two clocks, one in the nose and one in the tail, that have been sync'd in the frame of the rocket. A clock on the ground and the clock in the nose of the rocket both read zero as they...
  38. paulmdrdo1

    MHB Distance Traveled by Clock Hour Hand in 1hr 20min

    if the hour hand of a clock has a length of 4 in. how far does its tip travel in 1hr and 20min?
  39. L

    Problem in reading the 2nd data from pcf8563 real time clock by i2c

    Suppose the 2nd data can be read after the first data, but i need to restart the condition the only can read the 2nd data. By that, i have read the slave address again before the 2nd data has been read. So how should i solve it?
  40. Y

    How Can a Mechanical Town Clock Be Modified to Chime Every Second?

    I just wanted to know how a town or a tower clock works. I would like to know if I can device a mechanism such that I will be able to use the striking train to strike every second, loud and clear i.e. I must get a loud chime every second but without using an electrical supply.
  41. QuantumCurt

    Finding length of minute hand of clock

    Homework Statement The minute hand of a clock travels 6.28 inches in 15 minutes. Find the length of the minute hand. Approximate to the nearest inch, if necessary. The Attempt at a Solution I figured the arc length to be \frac{\pi}{2} because it's traveled one quarter of the...
  42. A

    When Clocks Meet: Investigating Time in Einstein's Special Relativity

    Dear Friends, Discussion of the Einstein's Special Relativity clock paradox is often complicated by the role of accelerations and objects following curved or polygonal paths. In the following example considers the clock paradox in a situation which only involves linear motion. Imagine a rod...
  43. A

    Angle Between Hour & Second Hand:130.25° or 133°?

    a clock was set 10 am 20 minutes 30 second ? what will be the angle between hour & second hand ?? ans : 130.25° or 133° which one is correct? I'm confused
  44. E

    Time-dialation and light clock

    Can someone explain exactly(or to the best of your abilities) the changes that the light clock goes through from being in a stationary position, to reaching the speed of light? How does the light clock work, and how does the distance between "ticks" change to result in the slowing down of time...
  45. J

    Is a Universal Clock Possible? Answers Here

    Is it possible for the to be a universal clock that someone outside of the universe could time events with, and view the different ways that time travels in the universe?
  46. E

    Designing a Femptosecond clock.

    Hi, I had an idea for creating a clock that could time femptoseconds, although it's possible that this design would most likely fail and only create some crazy diffraction patterns, but anyway, here was my idea (I also didnt' want to waste forum space anywhere else but General Discussion with...
  47. X

    Digital Clock Project w/ 7490 IC - Strange Problem

    Hello! So my current project is to make a digital clock using primarily the 7490 IC. Which, (to those not familiar) is just a decade counter that outputs a 4 bit binary number. I am having a very strange problem. I made a video that explains everything. (Since it just seemed easier to...
  48. marcus

    Switch to scale factor time (universe its own clock)

    Switch to scale factor "time" (universe its own clock) In a sense the universe is its own clock and the pointer-hand is the scalefactor, as in: "when distances were 0.1 what they are today" "when distances were 0.3 what they are today" "when distances were 0.9 what they are today" For some...
  49. B

    How to make the clock refresh instead of it repeating every second

    I did the following program #include<stdio.h> #include <stdlib.h> #include <time.h> int main (void) { int sec,min,h; printf("please enter the the time in the following format hh:mm:ss :"); scanf("%d:%d:%d",&h,&min,&sec); for ( ; ; ) { sleep(1);// a delay function which delays by a second...
  50. J

    The atomic clock on a jetliner experiment

    Something I don't understand about that experiment, or about relativity in general. Why the clock on the jet flying around the world is the slower one. I mean isn't the stationary clock moving the same speed away from the jetliner clock relative to the jetliner clock?
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