What is stones: Definition and 50 Discussions

In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its chemical composition, and the way in which it is formed. Rocks form the Earth's outer solid layer, the crust, and most of its interior, except for the liquid outer core and pockets of magma in the asthenosphere. The study of rocks involves multiple subdisciplines of geology, including petrology and mineralogy. It may be limited to rocks found on Earth, or it may include planetary geology that studies the rocks of other celestial objects.
Rocks are usually grouped into three main groups: igneous rocks, sedimentary rocks and metamorphic rocks. Igneous rocks are formed when magma cools in the Earth's crust, or lava cools on the ground surface or the seabed. Sedimentary rocks are formed by diagenesis and lithification of sediments, which in turn are formed by the weathering, transport, and deposition of existing rocks. Metamorphic rocks are formed when existing rocks are subjected to such high pressures and temperatures that they are transformed without significant melting.
Humanity has made use of rocks since the earliest humans. This early period, called the Stone Age, saw the development of many stone tools. Stone was then used as a major component in the construction of buildings and early infrastructure. Mining developed to extract rocks from the Earth and obtain the minerals within them, including metals. Modern technology has allowed the development of new man-made rocks and rock-like substances, such as concrete.

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  1. MatinSAR

    Distance as a function of time for two falling stones

    I am aware that this question is very simple and basic. Using ##y(t)=y_0+v_{0,y}t-\frac {1}{2}gt^2## we can find distance as a function of time: ##|y_1-y_2|=|y_0+v_{0,y}t|=-y_0- v_{0,y}t## I assumed the downward direction to be negative. So as I wrote ##D(t)=-y_0- v_{0,y}t##. It tells that the...
  2. jim mcnamara

    Hungersteine -> "hunger stones" hydrologic markers of famine

    " Carved into the side of a rock, the phrase emerged as water levels continue to drop in one European river, and the five-word translation delivers a warning from ancestors of what’s to come. -- Allison Finch, AccuWeather staff writer Published Aug. 15, 2022 12:08 PM MDT | Updated Aug. 15, 2022...
  3. philo

    How much pressure in PSI was needed in the Ancient World to cut stones?

    Was watching a video on the the Great Pyramid of Giza and it got me wondering how one might cut one of the stones. Doing a couple google searches, I thought that a Venturi pump would likely be the means by which the stones were cut. The problem being how would they get a large enough psi...
  4. robphy

    RIP Charlie Watts (Rolling Stones)

    As a high school student, I remember getting tickets to the Tattoo You tour. I was going redeem a voucher to buy tickets in New York City (these vouchers were distributed by randomly selected self-addressed stamped envelopes). A few blocks from the box office, I was offered $500 for my voucher...
  5. H

    Throwing two stones, find the velocity of the second stone

    Homework Statement A man let a stone from height 49 metres. After 1 second he threw a second stone. Both stones fell on same time. What is the velocity of second stone? Homework Equations h=1/2gt^2 h=1/2a(t-1)^2 The Attempt at a Solution So I assume that if he let the first stone then the...
  6. O

    Projection at an angle - throwing stones

    Hello everyone. I have this problem: 1. The problem statement, all variables and given/known d I throw stone from height h at an angle α, then at an angle β (so I know h, α, β). I throw it with same velocity v. The stones fall in same distance d. The question is: find the d (distance) and v...
  7. davenn

    Thunderstorm produced huge hail stones in Belarus 13 July

    From a fellow stormchaser in Europe GIANT hail up to 10 cm diameter in Talacyhn area, Vitsebskaya region, Belarus on July 13 https://scontent-syd1-1.xx.fbcdn.net/v/t1.0-9/13697084_1838281166394976_2089999493087491553_n.jpg?oh=028e330c98a65bc55ed26fe5841d343c&oe=57E9B763very effective car and...
  8. MarcozXD

    Should carbon boiling stones be used in O-chem reactions?

    I performed column cromatography on an oil, and used carbon boiling chips but got some weird IR. I used hexanes and acetone as solvents, I am trying to figure out some of the spikes, soo I am thinking that maybe the boiling stone being carbon could acted as activated carbon and absorbed some...
  9. E

    Is there a way the ancients moved giant stones without machinery?

    Not that I believe Ancient Aliens but is the pulley and log theory really that solid?
  10. Ritzycat

    Sound: Stones falling from cliffs

    Homework Statement A stone is dropped from the top of a cliff. The splash it makes when striking the water below is heard 2.1s later. The speed of sound in air is 343 m/s. How high is the cliff? Homework Equations Δx=½at^2 t_1+t_2=2.1s t_2=x/343m/s The Attempt at a Solution I used those...
  11. M

    When Do Two Stones Meet in the Air?

    Homework Statement Suppose you throw a stone straight up with an initial velocity of 20.5 m/s and, 4.0 s later you throw a second stone straight up with the same initial velocity. The first stone going down will meet the second stone going up. At what height above the point of release do the...
  12. Y

    Where Do Falling and Projected Stones Meet?

    Homework Statement This is a very simple question. I even got the answer but I don't exactly I got it. Here it is: A stone is allowed to fall from the top of a 100 m high and at the same time another stone is projected vertically upwards from the ground with a velocity of 25 m/s. Calculate...
  13. A

    Finding the time when two stones cross paths

    Homework Statement Two stones are thrown simultaneously, one straight upward from the base of a cliff and the other straight downward from the top of the cliff. The height of the cliff is 6.69 m. The stones are thrown with the same speed of 9.97 m/s. After what time do the stones cross paths...
  14. P

    Calculating Vertical Stone Throw Intersection Time and Altitude

    Homework Statement A stone is thrown up vertically from the ground (the gravitational acceleration is g=10 m/s2). After a time Δt= 1 s, a second stone is thrown up vertically. The first stone has an initial speed v1= 7.0 m/s, and the second stone v2= 7.0 m/s. (a) At what time t after the...
  15. S

    Irrigation from artificial paving stones?

    Would it be possible to design a paving stone with a reservoir of some kind under it that would let water drain through the stone into the reservoir and then very gradually seep into the ground around the stone? In a dry climate, the goal would be to create an area of a lawn that was part...
  16. G

    Why do stones bounce off the water?

    Why does a stone bounce off the surface of the water? Why does a bullet bounce off of the surface when it strikes a material at an angle? When I was learning about why glass water bend light, the use of a toy car rolling over different surfaces was used. The slowing down of one side of the...
  17. zoobyshoe

    Medical Kids with Kidney Stones: A Growing Concern?

    A friend of mine just got told by a doctor he might have kidney stones. I was a bit shocked since he's 24. Googling, I found this: http://www.nytimes.com/2008/10/28/health/28kidn.html
  18. B

    Whiskey Stones - ice, stone, steel: which is best?

    "Whiskey Stones" - ice, stone, steel: which is best?? The conundrum: I'd like to purchase the most effective cooling item for my evening dram of scotch, or Manhattan bourbon, or Black Label, or... Where was I? Seriously, I am intrigued by the growing popularity of "whiskey rocks" - an item to...
  19. L

    Stones thrown from different heights

    Homework Statement Two stones are thrown from different heights and at different times. While they are still in flight ,find the functional form of the vertical distance between them as a function of time Homework Equations ? How do you do this, there are no numbers given I am very...
  20. O

    Questions about some stones

    Hey, I have some questions about some stones we got from an old lady. I can post pictures of them, I'll start in a few moments. :) Any information about them would be greatly appreciated x
  21. W

    Two stones dropped at the same time. Quick question, .

    Homework Statement Two identical stones are dropped from a tall building, one after the other. Assume air resistance is negligible. While both stones are falling, what will happen to the vertical distance between them? Homework Equations a) It will increase. b) It will first...
  22. S

    Kinematics equation problem. (two stones dropped from different heights)

    Homework Statement Two identical stones are dropped from rest and feel no air resistance as they fall. Stone A is dropped from height h, and stone B is dropped from height 2h. If stone A takes time t to reach the ground, stone B will take time: a. 2t b. t/2 c. 4t d. t /(square root of...
  23. S

    Collision of marbles and stones

    1. Question: A 100g stone rests on a fricionless horizontal surface. A marble of mass 40g, traveling horizontantally at 30m/s strikes the stone and rebunds horizontally at right angles to its original direction wiht a speed of 20m/s. What is the velocity (magnitude and direction) of the stone...
  24. K

    Solving for Velocity & Time for 2 Stones Projected Vertically with Same Initial Velocity

    Homework Statement A stone is projected vertically with a initial velocity u. Another stone projected from the same position verticaly with same velocity u after time t. Find the velocity of both stones when they meet together & time taken to meet. Homework Equations S = ut + 1/2 at2...
  25. A

    Stones being dropped and thrown from building

    Homework Statement A stone is dropped from the roof of a building; 1.90 s after that, a second stone is thrown straight down with an initial speed of 29.0 m/s, and the two stones land at the same time. a. How long did it take the first stone to reach the ground? b. How high is the...
  26. H

    1D Kinematics - 2 stones thrown - where do they meet?

    Homework Statement Two stones are thrown simultaneously, one straight upward from the base of a cliff and the other straight downward from the top of the cliff. The height of the cliff is 5.85 m. The stones are thrown with the same speed of 8.59 m/s. Find the location (above the base of the...
  27. N

    Conservation of energy of two thrown stones

    Homework Statement Two stones are thrown with the same initial speed at the same instant from the roof of a building. One stone is thrown at an angle of 30 degree above the horizontal; the other is thrown horizontally.(Neglect air resistance.), which of the following is true: (a)The...
  28. P

    Calculating Time Interval of Splash from Two Stones Dropped

    A mountain climber stands at the top of a 59.4 m cliff that over hangs a pool of water. He throws 2 stones vertically downwards 1.77s apart and they cause a single splash. first stone initial velocity= -2.06m/s acceleration of gravity 9.8m/s^2 How long after release of first stone will the...
  29. Z

    Comparing Two Stones: Solving the Mystery of Height and Time

    I've been kicking myself in the head all day trying to figure this one out. I'm completely bewildered.:uhh: Please help meeee! A stone is thrown vertically upward at a speed of 43.00 m/s at time t=0. A second stone is thrown upward with the same speed 2.250 seconds later. At what time are...
  30. M

    Two Stones Thrown Upward: Solving the Problem

    Hey guys, I am new here, i was wondering if you could help me solve the following problems ok...A stone is thrown vertically upward at a speed of 48.70 m/s at time t=0. A second stone is thrown upward with the same speed 4.390 seconds later. At what time are the two stones at the same height...
  31. L

    Calculating Stone Distance and Speed: Kinematics Problem Help

    Homework Statement A stone is dropped from the roof of a high building. A second stone is dropped 1.50 s later. How far apart are the stones when the second one has reached a speed of 11.0 m/s? Homework Equations kinematics The Attempt at a Solution i need help setting up the...
  32. ~christina~

    A climber throws 2 stones 1.00s apart and they hit at the same time

    A climber throws 2 stones 1.00s apart and they hit at same time h=50ft height of cliff = 50ft I think there is enough info now... Homework Statement A climber climbs a cliff overhanging a calm pool of water and throws 2 stones vertically down 1.00 s apart. The climber then observes that...
  33. S

    Solving Physics Problems: Dropped Stones, Thrown Balls, and Falling Tiles

    1. A spelunker (cave explorer) drops a stone from rest into a hole. The speed of sound is 343 m/s in air, and the sound of the stone striking the bottom is heard 1.64 s after the stone is dropped. How deep is the hole? 2. A ball is thrown upward from the top of a 25.0-m-tall building. The...
  34. J

    Medical Suffering from Kidney Stones: My Story

    Who here suffers from kidney stones? I have been passing them from time to time since I was 30. I started out slowly, but in the past few years it's been two a year. I had a couple removed surgically including one that was an inch in diameter. I mention it because I just passed one earlier today...
  35. Ivan Seeking

    Horses getting wasted for Stones gig causes backlash

    http://www.cnn.com/2007/SHOWBIZ/Music/04/18/stones.horses.reut/index.html?eref=rss_topstories
  36. R

    Calculating the Distance Between Two Stones Dropped Off a Cliff

    2 stones are dropped off a 60 m cliff the second stone is droped 1.6 s after the first one. how far below the top of the cliff is the second stone when th separation between the 2 stones is 36 m? so i am trying to use the equation x1=xo+tvo+.5at^2 then x2=xo+(t+1.6)vo+.5a(t+1.6)^2 or...
  37. mbrmbrg

    Two Falling Stones and Their Center of Mass

    A stone is dropped at t = 0. A second stone, with twice the mass of the first, is dropped from the same point at t = 250 ms. (a) How far below the release point is the center of mass of the two stones at t = 600 ms? (Neither stone has yet reached the ground.) (b) How fast is the center of...
  38. B

    Calculating Force of Hail Stones on a Roof

    I cannot know how to calculate the force of the hail :bugeye: During a violent thunderstorm, hail the size of marbles (diameter = 1.20 cm) falls at a speed of 14.0 m/s. There are estimated to be 110.0 hailstones per cubic meter of air. Assume that, as for ice, 1.00 cm3 of hail has a mass of...
  39. O

    Another aggravating kinematics problem - regarding stones

    A stone is DROPPED off a 144 foot cliff. A second later, another stone is THROWN off that cliff. The two hit the water at the same exact instant. What is the initial velocity of the second stone? The answer is 40 ft/second according to my book, but for some reason, I never get that. I...
  40. B

    Can someone help me with this problem. Two stones being thrown straight up

    A stone is thrown vertically upward at a speed of 18.00 m/s at time t=0. A second stone is thrown upward with the same speed 0.880 s later. (a) At what time are the two stones at the same height? (b) At what height do the two stones pass each other? (c) What is the upward speed of the second...
  41. J

    Calculating the Intersection of Two Stones Dropped from a Cliff

    A stone is droped from the top of a cliff of height 256 feet, and, at the same instant, another stone is projected vertically upwards from the ground with a speed of 96 ft/s. Find where they will meet? I have the following: v1=u1+at, v2=u2+at, s1=u1t+1/2at^2, s2=u2+1/2at^2, I also have...
  42. R

    Boiling Stones: What You Need to Know

    What is the purpose of boiling stones and why wouldn't you add one to an already hot liquid? Thanks for the help.
  43. B

    Kinematics problem two stones falling one with velocity one at rest

    hi please can sum one help me, a stone is dropped from he top of a cliiff at rest another stone it thrown downwards from the same point at 11ms-1. The two stones land at the same time, what is the height of the cliff,:frown: how do u work this out i have no idea,:cry: thankyou in...
  44. J

    Solve Stones and Velocity: 18 m/s, 11m, 0.77 sec

    Question: A stone is thrown verticall upward with a speed of 18.0 m/s. (a) How fast is it moving when it reaches a height of 11.0m? (b) How long is required to reach this height? a. Work v(i)=18.0 m/s x=11.0 m x(i)=0 g=9.8 m/s ^2 v=? v^2=v(i)^2-2g(x-x(i)) v^2=18^2-2(9.8)(11-0)...
  45. Ivan Seeking

    Mysterious Girl Who Wept Stones Admitted to Hospital

    http://www.nzherald.co.nz/latestnewsstory.cfm?storyID=3601957&thesection=news&thesubsection=world
  46. P

    How can we use a catapult to study the properties of skipping stones in physics?

    We are the same Swedish team competing in a worldwide Young Physicists tournament for K-12 students. We're currently getting a grasp of the formulas involved and meanwhile we need a way to prove them. Or initial idea is to create some sort of catapult with which we can slung a stone at a...
  47. E

    The Dropa Stones: Unraveling a Mysterious Archaeological Find

    This site claims to have the story of one of the most mysterious archaeological finds of all time. I'm curious and skeptical as to how the language was decoded. http://www.subversiveelement.com/DropaStones.html
  48. E

    Newtons does a 40 kg bag of stones weigh

    how much in Newtons does a 40 kg bag of stones weigh? my answer is 302 Newtons is that correct?
  49. Ivan Seeking

    Deep Water Megalithic Stones and Structures Near Western Cuba?

    I have been hearing about this story for some time. I have no idea what to think. It seems to be a step above the typical fringe story so I posted here. http://www.earthfiles.com/news/news.cfm?ID=587&category=Science
  50. M

    Calculating the Time and Height of Falling Stones: A Kinematics Problem

    Ok, so there are two stones. One is dropped (not thrown) off a building. 2 seconds later a rock is thrown at 30 m/s. The rocks hit the ground at the same time. Here's what I have so far: R1: v0 = 0 m/s T = unknown x = o m x0 = unknown a = 9.8 m/s^2 R2: v0 = 30 m/s T = Time...
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