time

  1. L

    Expression of power

    Power is defined by P=W/t where W is work done and t is the time. If force F is constant, then power can also be P=Fv where v is the velocity, which sort of can be derived from P=W/t=Fs/t=Fv. Since F=ma, also P=mav..........(1) However, if work done is turned into kinetic energy, E=(1/2)mv^2...
  2. bravopipo

    Spring related problem, force time mass and displacement

    Hello, Kindly solve this problem for me, or at least give me the procedure of equation to use. I don't know how to begin because I have not found any relationship that relate spring constant to time. If you find the solution, give me numerical result. We have (see the picture): 1. A...
  3. S

    What is the true way to determine time parameters from semilog graph?

    Hi all, I have experimental nuclear magnetic resonance data that describe T2-relaxation of the nuclei in the sample of interest. The experimental points obey bi-exponential dependence: I = I1*exp(-t/T2_1) + I2*exp(-t/T2_2), where I is current intensity, I1 and I2 are intensities which represent...
  4. S

    Time between Asteroidal Impacts Help pls!!

    If someone could help me with this question I would be so grateful :) Consider the Astroid belt as a torus surrounding the sun, populated by 1 million astroids, and with an astroid number density N = 2.3*10^-20 astroids / km^3. For an impact parameter S = 0.5km, and an assumed relative...
  5. S

    Time required to cool an object using a fan

    Hello, A flat object with a known surface area is at a temperature of 285F. The ambient temperature in the room is 80F. The object needs to be cooled down to 100F within a time limit of 5 minutes. To accelerate the heat transfer process, there is a fan in the setup. The objective is to...
  6. P

    No start as time

    The reason we do not remember and do not know the start of time is that if we have start as time then it cannot be changed forever so there can be no mistake to adjust it. And it means all of theory must be on time as forever but we still move and change time as reality for understanding physics...
  7. E

    Calculate the time it takes for river gravel to take on the same temperature as the a

    Heres the scenario: Water level drops in a river. The previously saturated gravel slowly takes on the same temperature as the air. Assuming the gravel was originally the same temperature as the water, and the surface is flat, How long does it take? I believe these are the relevant formulas...
  8. T

    Time of cars lapping on second/third lap

    Hi guys, I've got a problem involving a track and two cars. The problem appears to be a fairly simple simultaneous equation but actually turns out to be a bit more complex. Two toy cars start from the same position and race around a track. Both cars accelerate for 3 seconds. Car A...
  9. P

    Time line as relativity

    When rocket fly from the start point and meet the start point again as line, this means one term of time is ended. And when rocket move straight line forward, rocket can never meet the start point again. But when the rocket move forward straight line and backward straight line, it is the fast...
  10. I

    Why total time taken s₁/v₁ + s₂/v₂ + s₃/v₃ in average speed?

    As we know the Average speed = Total distance / Total time but why in the case below Distance traveled = s₁ + s₂ + s₃ and total time taken = s₁/v₁ + s₂/v₂ + s₃/v₃ How is it possible? Could you explain please? so, altogether Vav = s₁ + s₂ + s₃ / ( s₁/v₁ + s₂/v₂ + s₃/v₃)
  11. L

    What is a good definition of Time?

    Having checked there is not one really good definition of time yet in physics. Not a good definition for time in any dictionary I am aware of either. Here we are using a likely variable for years that we do not have even defined. Toward the end, in the paper I wrote about time and time...
  12. P

    Time by word

    Every word is logic as it is connected, but we(human being) take the words by our free will of God(It means philosophy that is history predicted.) and it can be connected by the word, God.(My English is sometime short as it is already done by other professional language but the different...
  13. A

    Sunlight Radiation on lake of ice (how long time take ice to melt) Exam soon Help!:)

    Hi Everyone, I am new here and I hope I can get help here. Sunlight with intensity (600 w/m^2) Occurs an ice-covered lake. 70 % of the intensity absorbed of ice, which is 1.4 cm thick. How long time take to melt the ice? I know those formulas (not including in questions): P = I 4...
  14. L

    Decay Rate of Cs Time

    Hello! Here is the question give to me by my teacher: A sample of 137Cs (half-life = 30.1 years) decays at a rate of 10^10 decays per second. How long will it take for the decay rate to decrease to 10^7 decays per second? The work I have done so far is: dN(t=0) = -λNo, where dN(t) =...
  15. K

    An unorthodox Speed vs Time to Speed vs Distance question

    Hi There, I'm doing some analysis work on a lab I ran recently for some of my undergrad thesis work.. and I think I've had a brain fart. I've got some recorded data which shows the speed of an object (in this case a towing carriage) over time. I need to get this speed-time plot to a...
  16. P

    No time cut

    There is the reason for the frame of physics formula, as they are made by time connection. So we are going forward on, forever, as new with no time cut, keeping the rule of normal physics theory. And there is the shape of theory as the frame. We are making one by one the frame continuously with...
  17. R

    Velocity time graph

    Really stuck on this... The velocity time graph of a diver who springs off of a board, up to a max height, and then down where he enters the pool and then swims through the water until he pushes off the floor of the swimming pool and then reaches the surface. The bit where he springs off...
  18. A

    Finding an expression for the velcoity v as a function of time.

    Here's the problem: Suppose an object with mass m is projected with initial velocity v 0 along the horizontal direction. Assume quadratic air resistance of the form F drag = αv^2 , where F drag is the magnitude of the drag force. Find an expression for the velocity v as a function of time...
  19. K

    A space time interval conundrum

    Here is a problem I have been pondering for the last week or so: In Peter Collier's book "A Most Incomprehensible Thing Notes Towards a Very Gentle Introduction to the Mathematics of Relativity" in section 3.3.5 he makes the following claim about the space time interval \Delta S^2 =c^2 \Delta...
  20. D

    Calculating g with time intervals of thrown object.

    At the National Physics Laboratory in England a measurement of the gravitational acceleration g was made by throwing a glass ball straight up in an evacuated tube and letting it return, as shown in the Figure. The time interval between the two passages across the lower level is equal to ∆TL =...