# What is Time interval: Definition and 62 Discussions

Time is the continued sequence of existence and events that occurs in an apparently irreversible succession from the past, through the present, into the future. It is a component quantity of various measurements used to sequence events, to compare the duration of events or the intervals between them, and to quantify rates of change of quantities in material reality or in the conscious experience. Time is often referred to as a fourth dimension, along with three spatial dimensions.Time has long been an important subject of study in religion, philosophy, and science, but defining it in a manner applicable to all fields without circularity has consistently eluded scholars.
Nevertheless, diverse fields such as business, industry, sports, the sciences, and the performing arts all incorporate some notion of time into their respective measuring systems.Time in physics is operationally defined as "what a clock reads".The physical nature of time is addressed by general relativity with respect to events in space-time. Examples of events are the collision of two particles, the explosion of a supernova, or the arrival of a rocket ship. Every event can be assigned four numbers representing its time and position (the event's coordinates). However, the numerical values are different for different observers. In general relativity, the question of what time it is now only has meaning relative to a particular observer. Distance and time are intimately related and the time required for light to travel a specific distance is the same for all observers, as first publicly demonstrated by Michelson and Morley. General relativity does not address the nature of time for extremely small intervals where quantum mechanics holds. At this time, there is no generally accepted theory of quantum general relativity. Time is one of the seven fundamental physical quantities in both the International System of Units (SI) and International System of Quantities. The SI base unit of time is the second. Time is used to define other quantities – such as velocity – so defining time in terms of such quantities would result in circularity of definition. An operational definition of time, wherein one says that observing a certain number of repetitions of one or another standard cyclical event (such as the passage of a free-swinging pendulum) constitutes one standard unit such as the second, is highly useful in the conduct of both advanced experiments and everyday affairs of life. To describe observations of an event, a location (position in space) and time are typically noted.
The operational definition of time does not address what the fundamental nature of it is. It does not address why events can happen forward and backward in space, whereas events only happen in the forward progress of time. Investigations into the relationship between space and time led physicists to define the spacetime continuum. General relativity is the primary framework for understanding how spacetime works. Through advances in both theoretical and experimental investigations of space-time, it has been shown that time can be distorted and dilated, particularly at the edges of black holes.
Temporal measurement has occupied scientists and technologists, and was a prime motivation in navigation and astronomy. Periodic events and periodic motion have long served as standards for units of time. Examples include the apparent motion of the sun across the sky, the phases of the moon, the swing of a pendulum, and the beat of a heart. Currently, the international unit of time, the second, is defined by measuring the electronic transition frequency of caesium atoms (see below). Time is also of significant social importance, having economic value ("time is money") as well as personal value, due to an awareness of the limited time in each day and in human life spans.
There are many systems for determining what time it is, including the Global Positioning System, other satellite systems, Coordinated Universal Time and mean solar time. In general, the numbers obtained from different time systems differ from one another.

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1. ### B Collision time interval of a gas molecule with wall of container

I have been trying to make sense of the derivation of pressure under Kinetic Theory of Gases chapter, but it's not making sense to me when the impulse momentum equation is used for the collision between a gas molecule and the wall of the container. The book says that for the elastic collision...
2. ### I Proper Time Interval: Exploring its Definition on Wikipedia

Wikipedia article on proper time "Given this differential expression for ##\tau##, the proper time interval is defined as ## \Delta \tau=\int_P d \tau=\int \frac{d s}{c} . ## Here ##P## is the worldline from some initial event to some final event with the ordering of the events fixed by the...
3. ### Zero velocity for a time interval, what about acceleration?

For a particle moving in a straight line, if the velocity is zero for a time interval, the acceleration is zero at any instant within the time interval. I am told the above statement is true. If I look at the equations v = dx/dt a = dv/dt It looks like if the velocity is zero for a time...
4. ### Time interval between intermediate passing of two rods....

The first part I have calculated is as follows:: Length of A seen by S =30m Length of B seen by S=40m In S frame, Time for front of A and B to come in same line 0.8ct=40+0.6ct...t=200/c From the above position time for back end of A and front of B to come in same line 0.8ct=30+0.6ct...t=150...
5. ### Calculating average acceleration during a time interval

Here's my calculations for (a) and (b)
6. ### MHB 2.6 Calculate the average velocity of the car in different time interval

OK I just had time to post and hopefully ok but still typos maybe the graph was done in Deimos wanted to try tikx but not sure about the polynomial trying to as many physics homework before classes start on Aug 26 Mahalo
7. ### Can instantaneous velocity be different from average velocity?

Homework Statement Is it possible for the instantaneous velocity of an object at some time, t1, to not be parallel to the average velocity over a short time interval, Δt=t2-t1? If it is not possible, explain why not. If it is possible, explain what this situation implies about the motion of...
8. ### Determining the time interval in a radiation counting problem

Homework Statement Given: Cn_dot = true event rate = 10 interactions/s p(t')dt' = differential probability of an event Homework Equations p(t')dt' = Cn_dot * exp(-Cn_dot * t') dt' The Attempt at a Solution [/B] I want to sample the time interval using python. But I'm not sure how to go...
9. ### Energy dissipated in a resistor during a time interval?

Homework Statement Homework Equations P = I*V energy dissipated = wr = ∫ ( P *dt) ... t is from 0 to .4 seconds vs = 400t^2 = 400 * (.4^2) = 64 V The Attempt at a Solution Using KVL I said Vs ( 64 V) = 100 * i ... I found that I was 64/100 = .64 amps. I then said power is .64 amps ^ 2 *...
10. ### Average velocity when the interval has a domain

Homework Statement If a ball is thrown into the air with a velocity of 40 ft/sec, its height (in feet) after t seconds is given by s(t) = 40t -16t^2. Find the average velocity, vAV (t), of the ball over the time interval (t, 2), for 0 < t < 2. Homework Equations change of x/change of...
11. ### Confused about Hooke's law when analyzed at different times

Homework Statement A.[/B] Suppose I have a block of mass 'M' that is attached to a wall via spring of coefficient 'k' , the spring has rest length Xo . Suppose I look at the problem at some time 't' such that the spring is being compressed and the block moves left ( moving towards x = 0 ) ...
12. ### Time Dilation - measured vs observed time interval

Homework Statement Consider an observer Bob in S standing close beside the x-axis as Alice, who is holding a clock, approaches him at speed VS'S along the axis. As Alice and her clock move from position A to B, Alice’s clock will measure a (proper) time interval ∆t0, but as measured by Bob’s...
13. ### What time interval between wave fronts in S and S'?

Homework Statement 1-9: Assume the train is 1.0km long as measured by the observer at C' and is moving at 150km/h. What time interval between the arrival of the wave fronts at C' is measured by the observer at C in S? [/B]Homework EquationsThe Attempt at a Solution The solution from the...
14. ### Best time interval for measuring capacitor discharge?

Homework Statement My (practise) coursework is to test the equation 'V = Vo e-t/RC' and choose values of R and C so that the voltage across the capacitor falls to half in 15 seconds. I decided it would be too difficult and inaccurate to record the voltage across the capacitor every 5 seconds...
15. ### Probability over time interval?

Homework Statement This is a problem I have posed for myself. Suppose I have found the probability of something occurring over an angle, so it is the probability of landing at a particular angle over an interval of 2 angles. How would I now find the probability of landing there within a...
16. ### Average speed over time interval

Edit Background: The teacher doesn't teach we just do activities and have whole chapters worth of 20 mini assignments due every few days. Yes I did read the book found nothing. 1. Homework Statement The average velocity of a car over a certain time interval is 35 mi/h. If the velocity of the...
17. ### Is this question missing a third time interval?

Homework Statement Given critical points (3,-4) and (6,0); interval of increase (3, infinity); interval of decrease (-infinity, 3), find the local maxima/minima and sketch the graph. Homework Equations No relevant equations are given, I believe it's a simple sketch the graph. The Attempt at...
18. ### Velocity and height at each time interval

Homework Statement I want to calculate velocity and height at each time interval Time intervals: 1,2,3 (seconds) equilibrium height = 3 meters amplitude = 0.2 angular frequency = 48 rad/s phase shift = 60 Homework Equations y(t) = equiheight + Amplitude*sin(angfre*t +...
19. ### (Relativity) Space Time Interval

Homework Statement Frames S and S' are moving relative to each other along the x and x' axes. They set their clocks to t = t'=0 when their origins coincide. In frame S, Event A occurs at xA = 1 yr and tA = 1 yr, while event B occurs at xB = 2 yr and tB = 0.5 yr. These events occur...
20. ### Proper Time Interval: A Puzzler

Hello. I'm having trouble figuring out from which perspective to measure the proper time interval for Special Relativity. In the textbook, the definition says it's "the time interval between two events measured by an observer who sees the events occur at the same point in space." But in the...
21. ### Proper time interval between two events

The course this question comes from is Modern Physics Homework Statement What is the proper time interval between two events if in some inertial reference frame the events are separated by 109m and 5s? Homework Equations I looked through my notes and under a the sub topic "Invariant...
22. ### Why Do Time Intervals Differ in Motion Analysis Problems?

Homework Statement From t=0 to t=5.00 min, a man stands still, and from t=5.00 min to t=10.0 min, he walks briskly in a straight line at a constant speed of 2.20 m/s. What are (a) his average velocity vavg (v average) and (b) his average acceleration aavg in the time interval 2.00 min to 8.00...
23. ### Determining the possible time interval between two sine waves

ok I just got stuck half way into a problem, I would like it if someone explained it! Ok the question says, two identical sinusodial waves with a wavelength of 3.0 m and traveling in the same direction with a v of 2m/s. Starting from the same point, just the second waves starts later. and the...
24. ### Find the time interval between the above two events.

Homework Statement A foreign fishing submarine moves straight north through Canadian waters at a constant velocity of 12 m/s and a constant depth of 150m below the surface. A Canadian helicopter is in pursuit, flying in exactly the same direction at a constant velocity of 52 m/s and a constant...
25. ### Instantaneous Speed in a time interval

Homework Statement In reference to Galileo's Inclined Plane experiment. 2) What does it mean to say “The ball picked up the same amount of speed in each successive time interval.” Use symbols to write this sentence mathematically. 5) For the ball falling vertically, if we believe that...
26. ### Finding the current for each time interval (Electric circuits)

Homework Statement The problem and its solution are attached as TheProblemAndSolution.jpg. 2. Relevant equation ν = L di/dt The Attempt at a Solution I don't understand how the solution gets i = 10.0 A for t = 2 ms as well as to how it gets i = 30 – (10 * 10^3) t) (A) for 2 ms < t < 4...
27. ### Position and time interval of a particle

Homework Statement The position of a particle moving along the y-axis has a position given by y = 0.20m + (8.0m/s) t - (10 m/s2) t2. is there any time interval during which the particle is not moving? Homework Equations The Attempt at a Solution I said No but I'm not sure why...
28. ### Probability distribution of the time interval between two cars

Hello, I am trying to solve the following problem from Sethna's book on statistical mechanics (not homework). On a Highway, the probability of a car passing in some interval dt is \frac{dt}{\tau}; \tau=5min. what is the probability distribution of time intervals \Delta between two...
29. ### Proper Time Interval: Explaining Δs Relationship

Could anyone explain how Δs is related to the proper time interval?
30. ### Can the proper time interval be < the coordinate time interval?

In general relativity, we have a gravitational time dilation of: \frac{d\tau}{dt} = \frac{1}{\sqrt{1 - \frac{2GM}{rc^2}}} The term - \frac{2GM}{rc^2} appears to be based on the fact that gravity is attractive. If I understand correctly, if the curvature of space-time leads to attraction, then...
31. ### How Does Time Dilation Affect Signal Reception from a Fast-Moving Spaceship?

Homework Statement We observe a spaceship moving away from the Earth at a velocity of v = 0.866c. The spaceship emits two light signals, the second one 4 seconds (Delta T') after the first one (measured on board). What is the time interval (Delta T) between the arrival of the two light signals...
32. ### Solving LC Circuits: Time Interval Between Max Current & Voltage

Homework Statement The total energy stored in an LC circuit is 2J. The inductance is 10^-2 H and the capacitance is 100 μF. What is the time interval between a maximum current through the inductor and a maximum potential difference in the capacitor?Homework Equations T = 2∏/ω ω = √(1/LC)The...
33. ### Calculating Time Interval and Speed of Inertial Clock

Homework Statement In the Home Frame, two events are observed to occur with a spatial separation of 12ns and a time coordination separation of 24ns. A)An inertial clock travels between these events in such a manner as to be present at both events. What timer interval does this clock read...
34. ### Help with average velocity during a time interval

Homework Statement The position of a particle in meters moving along the x-axis is given by: x=21+22t-6t^2 Calculate the average velocity of the object in m/s during the time interval t=1s to t=3s. Homework Equations x=21+22t-6t^2 t=3 ; t=1 v avg. = Xf - Xi/Tf - Ti = Δx/Δt don't...
35. ### Lasers- the avg power of the resulting laser pulse over a time interval

Homework Statement Suppose that total population inversion could be achieved in a ruby laser. If half of the electrons in E2 could then drop to E1 in 30 ns, what would be the avg power of the resulting laser pulse over this time interval? Assume that the ruby crystal is a cylinder 5.00cm long...
36. ### Registered events X in time interval t are distributed linearly n = n0

Registered events X in time interval t are distributed linearly n = n0 + bt. Find probability density function, then t = 10, n0 = 5 and b =2. Find average amount of registered events per day and Mean squared error. Find the probability to register an event per 5th and 6th days. What is the...
37. ### Time interval btwn 2 particles colliding (each with diff v and elevation)

Homework Statement Two particles are projected from the same point with velocities v1 and v2 at elevation α1 and α2, respectively, (α1>α2). Show that if they collide in mid-air, interval between firings must be: 2v1v2sin(α1 - α2)/g(v1cosα1 + v2cosα2) Homework Equations y = xtanα -...
38. ### Why is the Time component in the Space Time Interval negative?

Why is the Time component in the Space Time Interval negative? The space time interval is defined to be: ds^2=dt^2-dx^2-dy^2-dz^2 or depending on the convention used it may also be: ds^2=-dt+dx^2+dy^2+dz^2 The equation is defining distance using the pythagorean theorem. This results...
39. ### Distance Traveled by Point in Time Interval [1,3]

Homework Statement suppose the velocity of a point moving at time t, in seconds along a coordinate line is v(t)= (t+3)/(t^3+t) ft/sec. how far does the point travel during the time interval [1,3]. Homework Equations The Attempt at a Solution im not sure what to do, i used ∫3...
40. ### Space-Time Interval: Exploring Questions & Equations

I have two questions about the space-time interval question. I'm doing a little research about space time, and about space time intervals, but I'm not sure which equation to take. Some sources say that its s^2 = x^2 - c^2 t^2, other say its s^2 =c^2 t^2 - x^2. So which one do I take? The...
41. ### Exploring Spacetime Metric for Clock A's Time Interval

Consider the spacetime metric ds^2=-(1+r)dt^2+\frac{dr^2}{(1+r)} + r^2 ( d \theta^2 + \sin^2{\theta} d \phi^2) where \theta, \phi are polar coordinates on the sphere and r \geq 0. Consider an observer whose worldline is r=0. He has two identical clocks, A and B. He keeps clock A with...
42. ### Energy dissipated as heat during a time interval over resistor with constant pot. dif

Homework Statement How much energy is dissipated as heat over 2 minute time interval by a 1.5 k(ohm) resistor which has a constant 20 V potential difference across its leads? Homework Equations deltaV=-Ed The Attempt at a Solution In my notes this is the only equation that seems...
43. ### Time interval for atom collapse-rutherford model

Homework Statement the main drawback of rutherford atomic model was that from classical E&M theory ,an electron would radiate energy and thus the radius much decrease. how do i find the time interval over which the electron reaches r=0 when starting r=2.0 x 10^-10 m ??/ Homework Equations...
44. ### How Long Does It Take for a Car to Pass a Truck After Reaching the Speed Limit?

Homework Statement A car moving at a velocity of 20 m/s is behind a truck moving at a constant velocity of 18 m/s. When the car is 50 m behind the front of the truck, the car accelerates uniformly at 1.8 m/s^2. The car continues at the same acceleration until it reaches a velocity of 25 m/s...
45. ### Lorentz vs space time interval

Hallo. A question about the relationship between the formulas found using the Lorentz transform and the invariance of the space time interval. Two events A and B occur at the same time and different space locations in system S, where A and B are at rest and at distance x. The system S'...
46. ### Negative squares using the space time interval invariance

Hallo I'm new to this (wonderful) forum, and to SR too... I've a general question about the space time interval invariance. Say we have two points A and B, at rest each other, at distance AB. Now A and B simultaneously in their reference frame emit a flash of light. The space time interval...
47. ### Relativity - space time interval between 2 frames

Homework Statement In frame S, Herman drops a pizza at the same time that Pavel drops a marker. In frame S', Alice is moving relative to their S frame - What is the space time interval she sees? A. S' > S B. S' < S C. S=S Homework Equations Lorentz transformations is what we've been...
48. ### Space Time Interval: Solving Distance & C-Value

Homework Statement Homework Equations s2=c2(t2)-(x2) The Attempt at a Solution so.. s=72ly and t=100y c=c (72)2=(1)2(1002)-(x2) solving for x which is the distance i get x=69.39 aprox= 69. my question is when do we know to let c=1 or c=3*108 m/s how do we go back and forth between light...
49. ### Coupled oscillation: time interval between maxima

Homework Statement I calculated T_o to be 1.27 seconds and "T_o"' to be 1.23 seconds, each representing a normal mode of oscillation. These are correct according to the text. Here is the question: what is the time interval between successive maximum possible amplitudes of one pendulum after...
50. ### Time Interval for measuring Rate of Reaction

So we did a dry lab in class, and we were determining sources of error for a particular lab dealing with the measurement of rate of reaction. My teacher said that the time intervals of the recorded concentration was too far apart (1 minute intervals). I was wondering if anyone would explain...