Fall Definition and 922 Threads

Autumn, also known as fall in North American English, is one of the four temperate seasons. Outside the tropics, autumn marks the transition from summer to winter, in September (Northern Hemisphere) or March (Southern Hemisphere), when the duration of daylight becomes noticeably shorter and the temperature cools considerably. Day length decreases and night length increases as the season progresses until the Winter Solstice in December (Northern Hemisphere) and June (Southern Hemisphere). One of its main features in temperate climates is the shedding of leaves from deciduous trees.
Some cultures regard the autumnal equinox as "mid-autumn", while others with a longer temperature lag treat the equinox as the start of autumn. In the English-speaking world, autumn traditionally began with Lammas Day and ended around Hallowe'en, the approximate mid-points between midsummer, the autumnal equinox, and midwinter. Meteorologists (and Australia and most of the temperate countries in the southern hemisphere) use a definition based on Gregorian calendar months, with autumn being September, October, and November in the northern hemisphere, and March, April, and May in the southern hemisphere.
In North America, autumn traditionally starts with the September equinox (21 to 24 September) and ends with the winter solstice (21 or 22 December). Popular culture in the United States associates Labor Day, the first Monday in September, as the end of summer and the start of autumn; certain summer traditions, such as wearing white, are discouraged after that date. As daytime and nighttime temperatures decrease, trees change colour and then shed their leaves. In traditional East Asian solar term, autumn starts on or around 8 August and ends on or about 7 November. In Ireland, the autumn months according to the national meteorological service, Met Éireann, are September, October and November. However, according to the Irish Calendar, which is based on ancient Gaelic traditions, autumn lasts throughout the months of August, September and October, or possibly a few days later, depending on tradition. In the Irish language, September is known as Meán Fómhair ("middle of autumn") and October as Deireadh Fómhair ("end of autumn"). Persians celebrate the beginning of the autumn as Mehregan to honor Mithra (Mehr).

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  1. M

    Me, Thinking About A Jump and A Fall

    Hi all. I had grade 11 physics so I know the basics on physics.. grade 12 comes later this year... Anyways I was thinking about the systems in a jump, and the motion involved and I know motion physics work and all so don't get me wrong :P I'm not trying to disporve something here... I just know...
  2. Q

    Free Fall Problem: Solve for Water Speed Leaving Nozzle

    Homework Statement Suppose you adjust your garden hose nozzle for a hard stream of water. You point the nozzle vertically upward at a height of 1.5 meters above the ground. When you quickly move the nozzle away from the vertical, you hear the water striking the ground next to you for another...
  3. T

    Free Fall Acceleration fractures Problem

    Homework Statement Falls resulting in hip fractures are a major cause of injury and even death to the elderly. Typically, the hip’s speed at impact is about 2.0 m/s. If this can be reduced to 1.3 m/s or less, the hip will usually not fracture. One way to do this is by wearing elastic hip pads...
  4. A

    Free Fall: Find Time & Height for Passing Balls

    A ball is thrown upward with speed V. At the instant the ball is thrown, second ball is dropped from rest at a height H above the thrown ball, but not directly above it. Ignore air resistance. How much time elapses before the balls pass each other? Find a value of H such that the ball thrown...
  5. H

    Calculating Free Fall: Water Balloon Question | Math Homework Help

    Homework Statement A student at a window on the second floor of a dorm sees his math professor walking on the sidewalk beside the building. He drops a water balloon from 18.0 m above the ground when the prof is 1.00 m from the point directly beneath the window. The professor is 170 cm tall...
  6. V

    Free Fall Homework: Distance Between Window & Building

    Homework Statement A brick falls from the top of a building and drops past a 2.0 m tall window in 0.20 s. Determine the distance between the top of this window and the top of the building. Homework Equations v^2 = (v initial)^2 + 2ax The Attempt at a Solution 10 ^2 = 2(9.8)x...
  7. P

    How Long Does It Take for a Wrecking Ball to Fall to the Ground?

    1. A wrecking ball is hanging at rest from a crane when suddenly the cable breaks. The time it takes for the ball to fall halfway to the ground is 1.2 seconds. Find the time it takes for the ball to fall from rest all the way to ground 2. Vf=Vo-gt, Vf^2=Vo^2-2g(delta y), Yf=Yo+Vot-1/2gt^2 3. I...
  8. K

    What was the total time of fall?

    A ball, dropped from rest, covers three-sevenths of the distance to the ground in the last two seconds of its fall. (a) From what height was the ball dropped? _m (b) What was the total time of fall? _s For a, don't i need the final velocity to solve the problem? Vi=o A=-9.81? 2 days...
  9. G

    Application of Aristotle with free fall

    Homework Statement Aristotle believed that the time it takes for an object to fall a given distance is inversely proportional to its weight. Given objects A,B,C and D with weights of 10,40,20 and 30 grams, which one would have the heights terminal velocity if dropped from the same height...
  10. rocomath

    Courses Can I handle 5 math-driven courses in one semester?

    Ok, I originally wanted to do only take 4 courses so I could work at least 20 hours a week. Now I feel the urge to graduate so I found a 5th course. I go to University of Houston Abstract Algebra Advanced Linear Algebra 1 Differential Equations Intermediate Analysis Managerial...
  11. O

    The rise and fall of evidence-based natural philosophy.

    The rise and fall of evidence-based natural philosophy. The way we think of the external physical world — natural philosophy -- has in the past often been coloured by anthro’centric prejudice and personal egotism. This perspective has gradually been eclipsed by the secular ideal of...
  12. B

    AMD share price continues to fall.

    I'm curious to peoples opinions of AMD, I have been using AMD over Intel for a few years however Intel just released the new centrino 2's and AMD share price is still falling. Will AMD be able to keep up? I originally thought it could soon be a good time to buy AMD shares as they have a...
  13. I

    Read in a book that fall in a bh is the sameto go at c

    I have read in a book that fall in a bh is the sameto go at c. Is it true?
  14. A

    What speed will an object fall?

    I am looking for a formula to determine what speed an object will fall with a known height and weight. For example a 220 pound man falls from 65 ft, what speed will he be going when he hits the ground?
  15. N

    How Come Planets Don't Fall Into Stars?

    How come planets don't fall into stars as they orbit them? Einstein said a "space-time" curvature is caused because of the gigantic mass of the stars...why don't the planets orbiting these stars just fall right into them? Does it have something to do with the same reason why electrons never...
  16. S

    Going to RIT this Fall: Dual Majoring MicroE & Physics?

    Hello all! I am planning on going to RIT this fall into the Micro Electronic Engineering program. I realized after looking through my schedule for classes that there a lot of physics courses that are required. I was wondering if taking on MicroE and Physics as a dual major is too much to...
  17. K

    Finding Initial Velocity and Direction of a Ball in Free Fall

    A ball is shot out from a point A with initial velocity v. If it goes 55 meters in 4.4 seconds before it lands, what was the initial velocity and in what direction was the ball kicked? I first find the initial velocity in x-direction: 12.5 m/s. Then I use energy conservation in z-direction...
  18. S

    How Does Proper Time in Radial Free Fall Differ from Newtonian Predictions?

    Foster and Nightingale give an equation for the proper time of a radially falling clock between any two distances. (Short Course in General Relativity, 1979, p. 128.) As they state, the equation is the "same as its Newtonian counterpart." So there are no factors representing any slowing of the...
  19. A

    Why Does the Acceleration of Free Fall Differ at the Equator?

    Hello. Why is it so that the accelaration of free fall on a unit mass on equator = Gravitational force -Centripetel Force? Answer ample for a level purposes is required...
  20. L

    The probability of a rise or fall in blood pressure?

    The probability of a rise or fall in blood pressure?? I have developed a database program that searches for all blood pressure readings that are similar to the readings of any given patient. The program then retrieves the following day’s data from all the matching patients to find out what (if...
  21. B

    Free fall acceleration astronauts problem

    Homework Statement A starship is circling a distant planet of radius R. The astronauts find that the free fall acceleration of their altitude is is half the value at the surface of the planet. How far above the surface are they orbiting? The answer should be a multiple of R. Homework...
  22. B

    Does a Bird Immediately Fall When It Stops Flapping Its Wings?

    If a bird is in the air and for whatever reason it stops flapping it's wing, it'll fall back down. Is there a lag time between the stopping of the bird's wing and the fall? If there is, how long is it?
  23. T

    What Distance Does the Bucket Cover in 3.5 Seconds?

    [SOLVED] How far does the bucket fall? Homework Statement A cylindrical pulley with a mass of M = 5.7 kg and a radius of r = 0.66 m is used to lower a bucket with a mass of m = 2 kg into a well. The bucket starts from rest and falls for 3.5 s. The acceleration of gravity is 9:8 m/s^2 ...
  24. T

    Drugs for Closest Feeling to Being in Love?

    I am nieve in many ways. This is enitrely an innocent question from an innocent and curious person. Which drug (legal or illegal) gives the closest feeling/effect to a human of being in love? I guess there still recquires somoene that you desire present for the effect to occur? Or maybe only a...
  25. L

    How Deep Is the Lake and What Is the Initial Velocity of the Ball?

    Homework Statement A lead ball is dropped into a lake from a diving board 5.44 m above the water. It hits the water with a certain velocity and then sinks to the bottom with this same constant velocity. It reaches the bottom 4.84 s after it is dropped. (Assume the positive direction is...
  26. L

    Calculating Clay's Acceleration: 12.0 m Fall

    Homework Statement A ball of moist clay falls 12.0 m to the ground. It is in contact with the ground for 22.0 ms before stopping. (a) What is the average acceleration of the clay during the time it is in contact with the ground? (Treat the ball as a particle.) Homework Equations v^2 =...
  27. K

    How Fast Was the Ball Going When It Left the Incline?

    Homework Statement A ball rolls off an incline plane on top of a 1m high table and strikes the floor 62.5cm from the edge of the table. What was the velocity of the ball just as it left the incline plane? The incline is given as 30 degrees. I've put my frame of reference at the point where...
  28. M

    Programs Sooo I'll have a math degree in the fall

    Hrm, I had an account on here that I used to post with a while back, but I don't remember the name or password. Oh well. Anyway, I'm in a bit of an awkward situation. As the title says I'm going to graduate in the fall semester with a degree in math (and a physics minor). My passion is physics...
  29. rohanprabhu

    Adolf Hitler on the fall of HD DVD

    you might have already seen this.. but for those who haven't..
  30. M

    How Does Free Fall Affect a Ball's Motion and Vector Math?

    I am not very good at this so please help me someone. I am not sure if I am in the right forum or not but i can almost put money on you guys know these simple questions. 1. Which of the following statements applies to the motion of a ball rising and then falling in free fall? I. The...
  31. S

    Free fall far away from Earth (integral substitution problem)

    [SOLVED] Free fall far away from Earth (integral substitution problem) Homework Statement Given: v(x) = -v_1\sqrt{\left(\frac{R}{x} - \frac{R}{h}\right)} Find the time t. Homework Equations Listed above where v_1 , R , h are all constant. The Attempt at a Solution v(x) =...
  32. E

    How to Calculate Time it Takes for an Object to Fall or Reach the Top of an Arc

    If I'm given that someone releases a ball at x distance away from the ground how do you calculate how long it takes to fall? Another problem I have is finding the amount of time it takes to get to the top of an arc after you've thrown a ball and you're given the distance it is from the...
  33. T

    Why Electrons Don't Fall Into Nucleus of Atoms

    Hi, Why the electrons in an atom doesn't fall into the nucleus? May be because of wave-like building of the electron? Thanks.
  34. G

    Help- comparing objects in free fall

    Problem: An egg is thrown downwards at 2 m/s from the top of a bridge. At the same moment, a fisherman standing in a stream 30 m beneath the bridge throws a rock upwards at 15 m/s. How fast will the stone be moving when it and the egg are at the same height above the water? This...
  35. T

    Calculating Maximum Velocity of a Dropped Object

    A ball of mass .5 kg is dropped from a height of 5 m. What is the greatest velocity it will have just before hitting the ground? vf squared = vi squared + 2ad vf squared = 0 squared + 2(9.8)(5) vf = 9.8 m/s So the greatest velocity is 9.8 m/s, right? I am still very confuzzled and I think...
  36. H

    Is Free Fall Possible Without Air Resistance?

    Hey guys, when an object is free falling, is it still under the effects of air resistance? If it was not under the effects (an environment without air resistance) is free fall possible? (I am looking for an argument that it is under the effects of free fall but all replies will be taken into...
  37. JasonJo

    Graduate School Application Results and Strategies - Fall 2008

    Since every other message board has it, why not us? So what schools did you apply to and which ones did you get into? I applied to the following Math graduate programs: MIT Harvard Berkeley Stanford Princeton Chicago Columbia NYU Yale Cornell Texas UCSD Rutgers Duke UPENN...
  38. S

    What is the maximum height of a rocket in free fall?

    This free fall problem seems simple, but I can't get it. you have a rocket fired from rest with an acceleration of 40 m/s^2. It runs for 2.5 and then falls. I'm wanting to find the maximum height, which I think would require me getting the initial velocity first. v = v0 + at 0 = v0 + 40(2.5)...
  39. S

    Free Fall: Particle Velocity, Acceleration, Displacement

    A particle is launched vertically at an upward velocity of 39.24m/s. Neglecting air resistance what is the paricle's velocity on impact average acceleration average velocity and displacement after impact
  40. C

    Solving for Depth, Velocity, and Initial Velocity in a Free Fall Challenge

    [SOLVED] *****Another free fall challange!***** A lead ball is dropped into a lake from a diving board 5.06 m above the water. It hits the water with a certain velocity and then sinks to the bottom with this same constant velocity. It reaches the bottom 4.92 s after it is dropped. (Assume the...
  41. C

    How Do You Calculate Time and Distance in Free Fall Physics Problems?

    [SOLVED] Challenging problem (free fall) I am stuck with couple of problems and i keep getting the wrong answer. Perhaps my approach is wrong. Below are the questions and they way i approached the problems. A basketball player grabbing a rebound jumps 80 cm vertically. (a) How much...
  42. clope023

    Free Fall Motion - Max Height Reached by Helicopter

    [SOLVED] free fall motion Homework Statement A helicopter carrying Dr. Evil takes off with a constant upward acceleration of 5.0m/s^2. Secret agent Austin Powers jumps on just as the helicopter lifts off the ground. After the two men struggle for 10.0s , Powers shuts off the engine and...
  43. M

    Free fall height question - true/false

    Hey guys, I'm new here and need some help with a physics homework question. Two students stand on top of a building of height (h). One throws a ball straight upward at the same speed as the other student who simultaneously throws a ball straight downward toward the ground. Which of the...
  44. R

    Stunt people can fall from great heights

    Explain how momentum can be conserved in a collision when kinetic energy is not? Describe a situation in which it is desirable to have a highly inelastic collision. Explain why in this case. In motion pictures, stunt people can fall from great heights and land safely on giant airbags. Using the...
  45. P

    Free fall coordinates in Schwarzschild?

    Forgive a question from a mere piker in GR who has got interested in something he can't find the answer to: What is the metric and coordinates for a radial free-faller in Schwarschild? Let's specify we drop him radially from some r0 and he sets his clock to 0 and drops. I'm imagining...
  46. J

    Reducing Risk of Injury: The Impact of Air Bags on Stuntmen's Falls

    Question A stuntman lands safely in an air bag to break his fall from the top of a 6-storey building. Explain how the air bag reduces the risk of the injury. Attempts The air bag provides a longer duration for the force of the ground to act on the stuntman, hence the impulse is lesser, and...
  47. S

    Body Fall Kinematics: Find Time & Velocity at Impact

    Homework Statement A body falls from a height of 409.5m under gravity. Determine: (a) The time taken to reach the ground, if the initial velocity is zero (b) The velocity at impact with ground.Homework Equations s= ut v= u+at s=ut + 0.5*at^2The Attempt at a Solution i tried using the formulas...
  48. W

    How Long Until You Hit the Black Hole?

    Homework Statement Starting from rest at a great distance, you plunge straight towards a black hole of mass M. You set your watch to noon as you determine that you are crossing the horizon. How much more time do you have (as measured on your watch) until the instant of crunch? Homework...
  49. P

    Soluble Groups in Algebra: What Are They and What Branch Do They Fall Under?

    How does soluble groups fit into algebra? Why is there another name for it called solvable groups? What branch does it fall under?
  50. O

    Free Fall and max altitude Question

    A ball is thrown vertically upward from the ground with an intial speed of 15m/s. How long does it take the ball to reach its maximum altitude? What is its maximum altitude? Determine the velocity and accelartion of the ball at t=2s. If anyone can help me with the relatively simple problem...
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