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. K

    Analog Clock and Minute Marks Puzzle

    The minute hand of a 12 hour analog clock is situated precisely on a minute mark, while the hour hand is situated exactly 2 minute marks behind the minute hand. What time is it? Note: For purposes of the problem, each hour mark is deemed as a valid minute mark.
  2. edpell

    Gravity Clock: Pendulum Periods for Observers A & B

    OK here is a pendulum: A gravity clock consists of two spherical masses one large of rest mass M and one small of rest mass m. The smaller mass is suspended by a rigid frame, of negligible mass, at a height R above the center of the large mass. It is the bottom of a pendulum arm, of negligible...
  3. F

    A grandfather clock problem.

    Homework Statement The pendulum of a grandfather's clock activates an escapement mechanism every time is passes through the vertical. The escapement is under tension (provided by a hanging weight) and gives the pendulum a small impulse distance l from the pivot. The energy transferred by the...
  4. B

    Rotation rate of hour hand on clock?

    What is the rotation rate in revolutions per minute of the hour hand of a clock? a.) 1/(12x60) b.) 1/24 c.) 1/(24x60) d.) none of these I am not too sure how to answer this, i want to say its (a.) because it makes the most sense... ??any suggestions??
  5. A

    Clock Skew on PCs: Investigating Today's Accuracy

    Anyone know what a typical clock skew would be on your average PC these days? Updating my clock with NTP it appears my laptop (when running 24h and not in idle mode) drifts about 2 seconds a day. I get the impression that's a lot. (John Harrison was building better mechanical clocks 250 years...
  6. L

    Preception of time on a Clock.

    I have noticed that when one looks at a stopwatch or timer, which counts up or down respectively. if you watch the time being displayed continuously on the clock it seems smooth and uniform. Though if you watch them change, then close your eyes and open them in the middle of the change, the...
  7. O

    Medical Turning back the clock on aging muscles.

    This is some compelling new research... "A study led by researchers at the University of California, Berkeley, has identified critical biochemical pathways linked to the aging of human muscle. By manipulating these pathways, the researchers were able to turn back the clock on old human muscle...
  8. C

    Clock Oscillation: Q Calculation for 0.7 m Pendulum w/ 0.4 kg Bob

    Homework Statement A grandfather clock has a pendulum length of 0.7 m and a mass bob of 0.4 kg. A mass of 2 kg falls 0.8 m in seven days, providing the energy necessary to keep the amplitude (from equilibrium) of the pendulum oscillation steady at 0.03 rad. What is the Q of the system...
  9. M

    Vector clock and vector dog displacement problems

    Homework Statement The minute hand on a watch is 2.00 cm in length. What is the length (in cm) of the i hat component of the displacement vector of the tip of the minute hand from 8:00 AM to 8:20 AM? What is the length (in cm) of the j hat component of the displacement vector of the tip of the...
  10. A

    Light Clock in a Gravity well ?

    Light Clock in a Gravity well ? Hi Thinking of the effect on a light clock taken down to regions of greater gravitational dilation . it occurred to me that the only way there could be a decreased frequency was if light itself was moving slower. That the decrease in local speed would have to...
  11. F

    Beginner's Light Clock question

    I'm having a bit of trouble with the famous light clock example, where the photon bounces between 2 mirrors and the light clock is moving laterally across my view. The description is that I see the photon's path longer (spread out) and so it should take longer to travel between ticks. The...
  12. V

    External Clock usage on a msp430 dev tool kit

    Hi, I'm currently working with a MSP430F417x micro controller development kit. I need to drive the microcontroller with an external clock with a frequency of 10Mhz, the datasheets and other manuals don't exactly specify how I can go about with this, although there is a connextion on the board...
  13. D

    Thermal Expansion - Pendulum of a Grandfather Clock

    Thermal Expansion -- Pendulum of a Grandfather Clock Homework Statement The pendulum in a grandfather clock is made of brass (coefficient of linear expansion = 19 x 10^-6) and keeps perfect time at 17 degrees Celsius. How much time is gained or lost in a year if the clock is kept at 28...
  14. M

    Time dilation for clock thrown up and caught back

    If you throw up a clock in a field of gravity and it falls back down, will it show the same time as a clock that stayed at the surface? In other words, will the gravitational time dilation of the stationary clock exactly equal the sum of the smaller gravitational time dilation of the other clock...
  15. W

    What if light clock experiment was done on top of train?

    If the light clock was on top of the train, it wouldn't be in a inertial system. If a table tennis game was played inside the train, the ball would move as if played on the platform. But it wouldn't be possible ontop of the train. Does the light react the similarly to a table-tennis ball or is a...
  16. E

    How to divide a 24MHz clock to get 1kHz (in Verilog)

    Hey guys, I'm using the Altera Cyclone II FPGA Development Board, with the goal of controlling a relay. I need to divide 24MHz to get 1kHz, but I don't know how to write the code for it. I know one way to divide it, would be to have a 10bit counter, which will allow me to divide it by 1k...
  17. A

    Question about light clock.

    Often to describe relativity is used example with two ships. Ship B is traveling at 0.5c speed from ship A. Ship A is standing still and shooting out beam of ligth in direction of ship B. Ship B has this light clock which is placed verticaly. I understand the time delation with vertical clock...
  18. M

    Verify special relativity by concept light clock

    Verify special relativity by concept "light clock" Hello. For verify the special theory of relativity most books use a "light-clock": Obviously, the way the light covers, when the clock is moved is bigger, than the way the light covers when the clock is not move. Because speed of light...
  19. A

    Average velocity of clock hand

    The minute hand of a clock is 5.5 cm long. What is average velocity vector for the tip of the hand during the interval from the hour to 20 minutes past the hour, expressed in a coordinate system with they-axis toward noon and x-axis toward 3 o'clock? (Answer in terms of i-hat and j-hat...
  20. M

    Calculating direction of travel on a clock face

    This is not a a school or college question, it is just for my interest. Homework Statement suppose I travel 605 meters North , then travel 673 meters West. I have calculated shortest distance of Sq Root(605^2 + 673^2) = 905 meters What I am now trying to calculate is direction to face...
  21. E

    Looking for replacement for clock() function

    This function seems to be working incorrectly when I run my programm under wine on linux system. (program compiled with mingw32 on win32) Is there any other function that can give me more accuracy than 1 second? (i know time() is working well but i need something that changes a little bit more...
  22. O

    Simple Harmonic Motion and pendulum clock

    Homework Statement What will be better to take to the moon, a spring clock or a pendulum clock. Why? Homework Equations F= -k*(Delta)x k = g m/Dx T = 2*π*[square-root of:(m/k)] The Attempt at a Solution I know that there is less gravitational force while on the moon...
  23. W

    Ramsey fringes and the atomic clock

    Hi, I'm currently researching into the formation and history of atomic clocks. Quartz and crystal clocks can determine resonance frequency measurements to an order of 10^8, but using Ramsey fringes this can become more accurate. Could someone help me explain why Ramsey fringes are a far...
  24. N

    How Does a Chemical Clock Relate to Entropy?

    hi please give some me insight into the working of a chemical clock and its relation with entropy i don't really know if this is has anything to do with physics but please do help
  25. E

    Time dilation: period of a clock

    Relevant equations t' = t * sqrt(1 - v^2/c^2), where t' is the proper time interval, and t is the measured time interval in another reference frame. Homework Statement / Q: A spaceship is moving past us at a velocity of v = 3c/5. If, in our frame of reference, we measure a time...
  26. H

    Simple Harmonic Motion: Pendulum of Clock Replaced by Spring-Mass

    Homework Statement The pendulum of a clock is replaced by a spring-mass system with the spring having spring constant 0.1 N/m. What mass should be attached to the spring? Homework Equations T=2 pi (m/k)1/2 The Attempt at a Solution 1 = 2 pi (m/0.1)1/2 1 = 4 pi2 m/0.1...
  27. F

    Clock precision as a function of temperature and height above sea level

    Homework Statement A grandfather pendulum clock is to be moved from a location at sea level to a new location approximately 200 m up in height. We assume that the Earth's radius is 6400 km. We know Newton's gravitational law and the oscillation equation for a pendulum. (*) How much...
  28. G01

    Graduation clock is moving way too slowly

    Any other seniors out there think the graduation clock is moving way too slowly! I have to wait til May 31! It's killing me. I just want to get to grad school already! Sigh, I think I'll spend the next few months playing "Who has the Biggest Brain" on Facebook...:rolleyes:
  29. C

    Light Clock: Exploring Questions on Light Velocity & Motion

    I am a new fish to SR and I have some questions about light clock. Hope someone to clear my concepts. Q1. As we all know, the speed (scalar) of light is "c" and is independent to the motion of the light source, but what about the velocity (vector) of light (with magnitude "c" but what...
  30. M

    Clock Design for Zeta Zeros Mechanic Calculator

    I first met with the prime numbers problem at a greek novel and than I interested with the works of Cahit Arf. Please correct me , Zeta Function Zero is a proof to tell , there is a mechanical relation at all prime numbers , and there is a regularity. If this is correct , it would be very...
  31. T

    Understanding Time Dilation: Whose Clock Ticks Faster in Special Relativity?

    I have just started studying special relativity, and there is one thing I really don't understand: Suppose you have two observers, A and B, in space, and that these are moving relative to one another. Due to time dilation, their clocks will tick at different rates. But how do you know whose...
  32. B

    What happens inre time if a clock is independent of the motion of its reference body?

    Einstein wrote ... Q: What would happen inre (in regards to) time if, for any reason, a clock were to be 'independent of the state of motion of [its] body of reference'? A: _____ (?)
  33. Bob Walance

    Do clocks remain synchronized forever according to the equivalence principle?

    I did do some searching on this site for an answer to this, but couldn't find exactly what I was looking for. So, here it goes: First -- assume that the gravitational field that Jim experiences is "homogenous" (that is, constant magnitude and direction within his region of spacetime)...
  34. B

    External clock synchronization and sbsolute motion

    "External" clock synchronization and sbsolute motion The “external” clock synchronization goes as follows: Consider that the clocks C(x) located at the points M(x) of the OX axis of I inertial reference frame read all zero (t=0) as a result of a standard (Einstein) clock synchronization...
  35. C

    The Myth of the Biological Clock: Separating Fact from Fiction

    The "biological clock" thing You know that concept expressed as "my biological clock is ticking", the purported compulsion on the part of women to have children while all their girlyparts are still, er, reproductively in the black? Before Ol' Mother Nature, y'know, revokes the franchise? (The...
  36. C

    Rotational kinematics of analog clock

    When it is 10:00, the hour hand on an analog clock is 300 ahead of the minute hand. How many minutes elapse (to three significant digits) before the minute hand next points in the same direction as the hour hand? I seems really easy, but for some reason I am not getting the right answer...
  37. T

    Will CPU stock clock speeds ever exceed 4.0 GHz?

    The fastest stock clock speed I have ever seen on a CPU the is currently available to the public is the Intel Core 2 Quad 4.0 GHz. (it may be overclocked) For the past few years, clocks on CPU's never seemed to get substantially higher. Is there some kind of thermal limit to how fast you can run...
  38. W

    Building a 1KHz Clock Signal Timer using a 555

    I need to build a timer(using a 555) with a frequency of about 1KHz and a duty cycle of about 25% to provide my clock signal. So the 555 is obliviously in astable mode. From my engineering data sheet: D=\frac{R_B}{R_A+2R_B} f=\frac{1.44}{\left(R_A+2R_B\right)C} where C is my capacitance value...
  39. M

    Angular Speed of Clock Minute Hand: Rad/s

    Homework Statement What is the angular speed of the tip of the minute hand on a clock, in rad/s? Homework Equations I thought the equations needed would be angular velocity= change of theta/change in time. The Attempt at a Solution I worked on this one and am sure it has a...
  40. V

    What is Clock Pulse in Digital Circuits?

    wat is meant by the clock pulse given to the flip flops in digital circuits. Is it just a supply that is given to the ic as long as it is held in on position. How do some chips operate when the clock goes from high to low and not when pulses go from low to high?.
  41. K

    Explaining Length Contraction with the Light Clock Argument

    We're just learning special relativity in class and my lecturer uses the light clock argument (two moving clocks - one parallel and one perpendicular) to explain length contraction. I didn't quite get one thing about it. My notes say the light beam reflects at different times (i.e. they have...
  42. M

    Matter-antimatter ship in GR clock paradox - fuel consumption

    hi, recall the familiar round trip - it's more or less the same as in this arXiv article (http://arxiv.org/PS_cache/physics/pdf/0604/0604025v3.pdf) - round trip with acceleration g. me and my friends were wondering the following: imagine that the passenger abroad the rocket travels for 4...
  43. B

    Bondi k and everyday clock synchronization

    Dr.Greg has presented on the Forum the Lorentz-Einstein transformations (LET) expressed as a function of k=[(1+v/c)/(1-v/c)]1/2. The important fact is that the LET are clock synchronization independent. Because special relativity is a very flexible chapter of physics, I have tried to express...
  44. E

    Understanding alarm clock description

    https://www.amazon.com/dp/B000EX7LNM/?tag=pfamazon01-20 Can someone please explain to me what this means? What is "dual power and dual time"? Will it plug into my outlet or not (I have the type of outlet that is ubiquitous in the United States)? What is meant by "keeps proper time with 110 or...
  45. A

    Einstein's resolution of the clock paradox

    Einstein's resolution of the "clock paradox" I have read that most physicists believe that Einstein's resolution of the "clock paradox" or "twins paradox" is flawed and just plain wrong. I'm curious about what everyone here thinks about it. And I believe Einstein generally was interested in...
  46. B

    Negative Clock Readings: Compatible with Relativity?

    are clocks, displaying a negatve time, compatible with special relativity? thanks
  47. P

    Why the clock hands turn clockwise?

    Is that just by chance or there could be some possible reasons?
  48. A

    Which Clock Shows Less Time When They Collide?

    Simple question (derived from some unanswered posts from various posters, mostly mitesh9)... Two identical clocks A (stationary) and B (moving towards A) with a relative velocity v, so that it will collide with A after some time. (the notion of stationary/moving is for the sake of simplicity...
  49. T

    Circuit designs with crystals and layout of digital clock lines

    I have two different types of questions regarding crystals and clocks. I can't remember if I've asked these question before. I'd appreciate any input on this topic. Crystal external circuitry: Almost any IC with an external crystal has two pins to connect to it. Now my question is how...
  50. Y

    Will time travel ever come to an end?

    We say you have a machine that could go back and forth in time. The machine works roughly like this: A few seconds before you press the button to travel a week forth in time it will save like an autosave. Of course time will go on as if you had pushed the button which you had. You will disappear...
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