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Gravity force on a thrown ball problem

  1. Apr 17, 2009 #1
    A ball is thrown in the air at 44 m/s.

    How high does it go?

    How do you work this out?
     
  2. jcsd
  3. Apr 17, 2009 #2

    mgb_phys

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    Re: Gravity

    You know the equations of motion ?

    You have the initial speed, you know the acceleration and you know the final speed at the top of the curve.
     
  4. Apr 17, 2009 #3
    Re: Gravity

    You will want to use the 4th equation of motion.

    [tex]S=\frac{v^{2}-u^{2}}{-2g}[/tex]
     
  5. Apr 17, 2009 #4
    Re: Gravity

    so the answer is 98.8m, thanks!

    Can someone list the other equations of motion? Because I'm supposed to know them but cannot find them in notes or books :S
     
  6. Apr 17, 2009 #5
    Re: Gravity

    morgany,

    you shouldn't just memorize those formulas...find out how they came to be. start with Newton's laws and work in Newton's law of gravity. you may start to enjoy physics instead of seeing it as a chore of memorizing things.
     
  7. Apr 17, 2009 #6
    Re: Gravity

    oh come on. you cant find these formulas, are you having a laugh.

    www.google.com

    equations of motion

    first link.

    EDIT: i cant belive i wasted my 200th post on this.
     
  8. Apr 17, 2009 #7
    Re: Gravity

    Try http://en.wikipedia.org/wiki/Equations_of_motion

    But orthovector is right, you should learn why these formulas are correct not just memorize them.
     
  9. Apr 17, 2009 #8

    mgb_phys

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  10. Apr 17, 2009 #9
    Re: Gravity

    a lot of beginning physics students forget that the kinematic equations of motion work because there is constant acceleration. Many bad public physics teachers don't even tell the students about this fact, and they force the class of 30-40 kids to simply memorize these equations of motion. it's really an epidemic in the public school systems.
     
  11. Apr 17, 2009 #10
    Re: Gravity

    erm to be honest i just want an A at AS physics

    so all i need is the equations

    you utter neeks.
     
  12. Apr 17, 2009 #11

    mgb_phys

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    Re: Gravity

    Knowing when to use them might be handy

    You're welcome
     
  13. Apr 17, 2009 #12
    Re: Gravity

    sorry but xxchrisxx didnt have to be all sarcy about the fact that i couldn't find the equations for motion

    i got 115/120 when i took my first physics exam 6 months early, and the only reason i achieved this was by learning morbid equations from a spec.

    thanks to everyone that wasnt just trying to inject their own sense of pathetic humour into an online thread about physics.
     
    Last edited: Apr 17, 2009
  14. Apr 18, 2009 #13
    Re: Gravity

    Who cares what you've got in some test, certianly not me. Saying you cannot find the equations of motion shows only lazyness on your part.

    They are in pretty much every basics physics book concerning motion, and engineering book concerning motion. Most basic maths books concerning classical mechanics have it too. They are even clearly listed on wikipedia...

    I am willing to go out of my way to help anyone that shows at least some evidence that they have done some work themselves. You however have shown none of that. You merely demand we give you the answers when they are very VERY easy to find. Getting any grade in A level physics requires you to be able to locate and find information yourself, your attitude towards this is sorely lacking.


    Also the pm you sent is clearly against the guidelines of "Guidelines on Language and Attitude" Now I love hatemail at the best of times, your tears of fury make me happy. As im not feeling terribly vindictive, and it was more amusing than threatening it wont be reported this time.
     
    Last edited: Apr 18, 2009
  15. Apr 18, 2009 #14
    Re: Gravity

    Assuming you're taking A-Level mathematics (which I presume you are with physics) you need to memorise these anyway, as generally at least 1/4 of the mechanics questions require them, and they're not given to you. So as you so nicely put it, you'll need to do some more 'learning morbid equations from a spec.'
     
  16. Apr 18, 2009 #15
    Re: Gravity

    Actually I'm not doing A level Maths, because I'm only doing AS Physics.

    And Chris don't try and explain yourself, you were trying to make a wisecrack in order to either impress everyone else with your wit or to ridicule me.

    The hate mail was my brother, who shares this account with me, its his style to launch streams of swear words and abuse at others, while I'm just annoyed that you not only refused to help, but you went out of your way to attempt to mock me.

    In actual fact, I find physics a difficult subject in that there are a ton of equations that have no reference to the tiny specification of AS level physics. I presumed that searching for the laws of motion on google would result in a huge amount of A level, University etc. formulae which would only serve to confuse me.

    Therefore i went to this forum to ask somebody for equations related to this topic, instead receiving a rude and obnoxious joke left by somebody who appears to adopt a wholly different persona when in the anonymous environment that is the internet.

    All I was asking for was a bit of help and you decided to throw it back in my face. I wouldn't have done the same to you if you had asked me for the 5 Primary Precepts of the Natural Law theory or for how to say something in Spanish, I would have either ignored it or helped you out.

    There was no need for sarcy remarks like yours. They only serve to annoy others.
     
  17. Apr 18, 2009 #16
    Re: Gravity

    Hey, the time it took you to write that you could've found them 10 times over!

    Seriously, don't take the internetz so srs
     
  18. Apr 18, 2009 #17
    Re: Gravity

    It took me 5 minutes, and it was worth it if it has a shred of meaning to any of you. The problem with going on this forum is that I am surrounded by people obsessed with science and fact and not so much about thought. Nobody likes somebody that undermines somebody else, and they like it even less if they attempt to do it in a condescending and patronising ridicule.

    Just understand that, while I am attempting to get an A at AS Physics solely for the grade, I am at the same time attempting to explore the deep facets of the world and humanity, while the rest of you chase a well-paid job without regard to philosophy and ethics.
     
  19. Apr 18, 2009 #18
    Re: Gravity

    Oh really? And how would you pretend to know anything about anyone on this forum other than Chris who you seem to have a random vendetta against for calling it as it is. LAWL, as it happens, I'm not interested in taking physics at all further, the only reason I visit these forums is out of interest and wanting to help people as well as getting my questions of interest resolved.

    Get a clue, please.


    (sorry if i'm a bit abrupt) Edit: Re-reading this post i realise that I sound like a bit of a douche :F, but the facts remain
     
    Last edited: Apr 18, 2009
  20. Apr 18, 2009 #19
    Re: Gravity

    I can assure you I dont take fools lightly anyware, you would have got exactly the same responce if you were stood infront of me. If anything i'd have probably been far less diplomatic in person and told you in no uncertain terms 'on your bike pal' if you had acted in with the attitude you did.

    You should have searched first, and if you didnt understand something then I and many others would have taken all the time we could to explain the problems you were having.

    Coming here and demanding answers shows a very poor work ethic. Your immediate reaction to people telling you to actually work a little bit shows a poor attitude towards other people and the subject you are studing.

    Believe me if you are hurt and offended and consider me telling you to do work 'mocking you', you have some very harsh lessons to learn about life. Grow up, dont take offence if people tell you in no uncertain terms that you are being lazy as it probably means you are.


    Now if you ever have issues with physics, do a bit of work first if you are stuck I would be more than willing to help you. You give a little, you get a little.
     
  21. Apr 18, 2009 #20
    Re: Gravity

    lol this thread is hilarious

    sorry everyone
     
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