What is Rocks: Definition and 78 Discussions

A rock 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.
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 or 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 large pressures and temperatures that they are transformed—something that occurs, for example, when continental plates collide.The scientific study of the character and origin of rocks is called petrology, which is an essential subdiscipline of geology.

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  1. R

    How Do You Calculate Total Momentum of Two Connected Rocks in Motion?

    Homework Statement Two rocks are tied together with a string of negligible mass, and thrown into the air. At a particular instant, rock 1, which has a mass of 0.2 kg, is headed straight up with a speed of 2 m/s, and rock 2, which has a mass of 0.35 kg, is moving parallel to the ground, in the...
  2. F

    Optical phenomena with colliding river rocks

    Today, I was red-necking it up with some friends in Auburn at the nearby forest. We found an open area on a decent sized creek that was filled with mostly less-than-fist-sized river rock. After dark, we noticed that when a rock was thrown to the ground (on the other rocks), a small spirt of...
  3. M

    What is the maximum mass of rocks one can lift using a wheelbarrow PLEASE HELP

    What is the maximum mass of rocks one can lift using a wheelbarrow PLEASE HELP! Homework Statement A man is using a wheelbarrow to transport rocks across the garden. The man can generate a maximal vertical force of 500N to lift the wheelbarrow. If the centre of mass of the rocks is .25m...
  4. L

    Throwing Rocks: Analyzing Horizontal & Vertical Motion

    Homework Statement A rock is thrown at an angle of 17 degrees above the horizontal at 28.5 m/s, from the ground. a)How high will the rock rise above the ground? b)What is the horizontal speed of the rock at the top of its flight? c) How long will it take the rock to reach a vertical...
  5. J

    Why Does Deep Water Reduce Foot Pain from Rocks?

    Homework Statement If you have ever had to wade across a rocky creek while hiking in the mountains, you have probably noticed that by the time you get to the deep water in the center of the creek rocks don't seem to hurt your bare feet as much. what is the reason for this? a. one tend to...
  6. Andre

    Oldest Rocks on Earth: 4.28 Billion Years in Canada

    http://news.bbc.co.uk/1/hi/sci/tech/7639024.stm It's not the oldest mineral though.
  7. L

    Geology of Lunar Rocks: Apollo Moon Landing Reality or Hoax?

    Hi, I am trying to find out about lunar rocks, the ones that came back from apollo. Moon landing hoaxers debunk the whole thing but in my mind, it seems unanswerable the idea that in the 60's and 70's we could have faked the moon rocks brought back. So, I am trying to see if I can close that...
  8. K

    Calculating the Height of a Cliff Using Rocks

    This problem doesn't have a diagram or a picture so: Suppose you land your spacecraft on a distant planet and disembark extremely close to the top-edge of a cliff. The planet's acceleration due to gravity is unknown and you want to know the height of the cliff. Utilizing your accurate...
  9. S

    What is the Final Velocity of the 18 kg Rock After Collision in Space?

    Homework Statement In outer space a rock with mass 4 kg, and velocity < 4000, -2800, 3400 > m/s, struck a rock with mass 18 kg and velocity < 250, -290, 260 > m/s. After the collision, the 4 kg rock's velocity is < 3600, -2300, 3900 > m/s. What is the final velocity of the 18 kg rock...
  10. M

    Motion problem with two rocks being released at different times

    Homework Statement the question is like this :you are in a balloon that is rising at a rate of 3.0m/s . you have two rocks. you release one when you are 50m above the ground. 2 seconds later you throw the other rock towards the ground . the two rocks hit the ground at the same time . what was...
  11. K

    Earth's rocks and Mars's rocks

    Having trouble with some homework. Why are there no rocks found as old as Earth is (apx. 4.5bil yrs)? Why are most rocks on Mars at least 3mil yrs old?
  12. F

    Calculating Distance Between Two Rocks When Thrown at 30 Degrees

    some body help me...it is very simple...somebody throws two rocks from the top of a hill, one above the horizontal line and the other rock below the horizontal line, at an angle of 30 degrees for both rocks and the inicial speed is 13m/s for both rocks as well...the quiestion is how far does the...
  13. L

    Identify Rocks from Lake Luzerne

    Could someone identify these rocks I collected at Lake Luzerne yesterday? http://sciencetexts.angelfire.com/lakeluzernerocks.html"
  14. Q

    How Do You Calculate Tension in a Two-Rock System in Circular Motion?

    Its just one of those days where my brain needs a bit of a jump start, if anyone could help me it would be greatly appreciated!Thanks! Problem: A rock of mass m1 = 0.4 kg is tied to another rock with a mass m2 = 0.58 kg with a string of length L1 = 0.14 m. The rock m2 is tied to another...
  15. X

    Tossing Rocks on Frictionless Ice: Calculating Angle and Speed

    While standing on frctionless ice, you (mass 65.0 kg) toss a 4.5 kg rock with initial speed 12.0 m/s. IF the rock is 15.2 m from you when it lands, (a) at what angle did you toss it? (b) How fast are you moving? I'm still having trouble with these.
  16. B

    Kinetic/Potential energy and thrown rocks

    A rock is thrown vertically upwards with a speed 'v' from the edge of a cliff. At the same moment, a second rock is thrown vertically downwards with the same initial speed 'v'. Which of the following statements regarding the motion of the rocks is true (ignore air resistance.)? a. The rock...
  17. Ivan Seeking

    Mysterious Force Rocks Gulf Coast

    http://www.wkrg.com/servlet/Satellite?pagename=WKRG%2FMGArticle%2FKRG_BasicArticle&c=MGArticle&cid=1128768768378&path=%21news%21local Earthquake or jet I would think...
  18. A

    News Earthquake in Asia: Over 19,000 Killed; International Aid Pours In

    http://news.bbc.co.uk/2/hi/south_asia/4324534.stm Come on Bush! $100,000 from the biggest ecconomy in the world. I hope this is just the tip of the icebergh as international aid goes...
  19. D

    How fast is the shell moving when it hits the rocks?

    Seagulls are often observed dropping clams and other shellfish from a height to the rocks below, as a means of opening the shells. If a seagull drops a shell from rest at a height of 14m, how fast is the shell moving when it hits the rocks? X= 1/2 gt^t i got 1.68945 secs do I round off to...
  20. S

    The Force of Gravity: Understanding Acceleration of 2-Kg Rocks

    The force of gravity is twice as great on a 2-kg rock on a 1-kg rock. Why does the 2-kg rock not fall with twice the acceleration?
  21. S

    Solving Two Physics Problems: Weighing Rocks and Steel Barbells

    Alright, these two problems are driving me nuts: 1. ---To verify her suspicion that a rock specimen is hollow, a geologist weighs the specimen in air and in water. She finds that the specimen weighs twice as much in air as it does in water. The solid part of the specimen has a density of...
  22. Ivan Seeking

    The Ringing Rocks of Pennsylvania

    http://www.unexplainedearth.com/ringing.php Well, I don't about about any mystery but an interesting site nonetheless.
  23. R

    Can an Asteroid Really Destroy Earth in 800 Years?

    I have seen many movies relating to the destruction of the Earth from space rocks and asteroids. Sometimes I think our planet might be attacked by such things. Even more I heard that scientist have observed an asteroid heading to Earth and might crash after about 800 years. Can this ever happen?
  24. P

    Who else works with electronic attack systems like the EA-6B Prowler?

    Hey, just joined the site, actually just found out about it! I'm glad I did, I haven't read about physics since college! I miss it, does that make me weird? Probably not here right? Anway, I fly EA-6B Prowlers for the Marine Corps as the ECMO(navigator and Electronic Countermeasures Officer)...
  25. A

    Rediscovering Hanoi Rocks: Is Anyone Else A Fan?

    Hey people i have recently purchased "up and around the bend, the definitive hanoi rocks collection" I think they where absolutely brilliant and the most underated band in history, their material is so unique, considering they are an 80's band. Has anyone else heard of these guys? If so...
  26. enigma

    Learn How to Use Mathmatica - Unsurpassed Symbolic Toolbox

    I have just taught myself how to use Mathmatica. The symbolic toolbox is outstanding! I have it running mass optimizations for modular rocket stages... something Matlab is (to my knowledge) unable to do symbolically , and crunching the numbers by hand takes at least 5 minutes per stage...
  27. H

    Mars rocks and Ancient Constructions?

    Listening to Richard Hoagland on late night radio and visiting his website : www.enterprisemission.com I see a lot of pictures of the planet Mars and lately a few shots taken of the Mars landscape showing a lot of rocks and Mars soil...only he claims these "Rocks" are possibly ancient...
  28. S

    A burbon on the rocks exists because ice is less dense than water

    I am fairly new to chemistry, so this might seem like a stupid question, but I am still interested nonetheless. A burbon on the rocks exists because ice is less dense than water, but how can this be the case when the molecules in a solid are closer together?
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