Results 1 to 8 of 8

Math Help - kinetic energy

  1. #1
    Senior Member
    Joined
    Jan 2007
    Posts
    477

    kinetic energy

    Point A is at a potential of +240 V, and point B is at a potential of -120 V. An -particle is a helium nucleus that contains two protons and two neutrons;

    the neutrons are electrically neutral. An -particle starts from rest at A and accelerates toward B.

    When the -particle arrives at B, what kinetic energy (in electron volts) does it have?
    in eV

    need help please.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,817
    Thanks
    316
    Awards
    1
    Quote Originally Posted by rcmango View Post
    Point A is at a potential of +240 V, and point B is at a potential of -120 V. An -particle is a helium nucleus that contains two protons and two neutrons;

    the neutrons are electrically neutral. An -particle starts from rest at A and accelerates toward B.

    When the -particle arrives at B, what kinetic energy (in electron volts) does it have?
    in eV

    need help please.
    W = q \Delta V

    What's q? What's \Delta V? How does the work done on the alpha particle relate to its kinetic energy?

    -Dan
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Senior Member
    Joined
    Jan 2007
    Posts
    477
    q is the charge stored by a dialectric capacitor.

    and change in V is the electric potential difference.

    chng in V = Vb - Va = -360 V correct?

    so where does the q come from?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Newbie
    Joined
    Jan 2008
    Posts
    5
    the answer is in EV maybe q has somthing to do with the electron? dont quote i have been out of school for too long
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,817
    Thanks
    316
    Awards
    1
    Quote Originally Posted by rcmango View Post
    q is the charge stored by a dialectric capacitor.

    and change in V is the electric potential difference.

    chng in V = Vb - Va = -360 V correct?

    so where does the q come from?
    No, the q is the charge on the alpha particle.

    Yes, \Delta V = -120~V - 240~V = -360~V.

    -Dan
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,817
    Thanks
    316
    Awards
    1
    Quote Originally Posted by Destiny666 View Post
    the answer is in EV maybe q has somthing to do with the electron? dont quote i have been out of school for too long
    The unit "eV" stands for "electron Volts." It is a unit of energy related directly to the amount of kinetic energy gained by a positron being accelerated over an electric potential of 1 V. 1~eV = 1.6 \times 10^{-19}~J.

    -Dan
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Junior Member
    Joined
    Sep 2007
    Posts
    66

    I am sure that is right

    Ek=(Vb-Va)xq
    = (-120-240)x2x1.602x〖10〗^(-19)
    =-360x3.204x〖10〗^(-19)
    ≈-1153x〖10〗^(-19)V[/SIZE]

    Ek is the kinetic energy
    Va is the potential at A
    Vb is the potential at B
    Last edited by blertta; January 23rd 2008 at 10:29 AM. Reason: My bad english
    Follow Math Help Forum on Facebook and Google+

  8. #8
    Forum Admin topsquark's Avatar
    Joined
    Jan 2006
    From
    Wellsville, NY
    Posts
    9,817
    Thanks
    316
    Awards
    1
    Quote Originally Posted by blertta View Post
    Ek=(Va-Vb)xq
    = (240+120)x2x1.602x〖10〗^(-19)
    =360x3.204x〖10〗^(-19)
    ≈1153x〖10〗^(-19)V[/SIZE]

    Ek is the kinetic energy
    Va is the potential at A
    Vb is the potential at B
    Except that they want the answer in eV. (By the way, your answer has the wrong unit! I think you meant "VC" which is equal to a J.)

    -Dan
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. kinetic energy during energy levels
    Posted in the Math Topics Forum
    Replies: 0
    Last Post: December 27th 2010, 01:12 AM
  2. kinetic energy PDE
    Posted in the Advanced Applied Math Forum
    Replies: 1
    Last Post: January 28th 2010, 07:55 AM
  3. Baseball - kinetic energy
    Posted in the Advanced Applied Math Forum
    Replies: 2
    Last Post: December 9th 2009, 05:55 PM
  4. kinetic energy
    Posted in the Math Topics Forum
    Replies: 5
    Last Post: January 6th 2009, 03:07 PM
  5. kinetic energy
    Posted in the Advanced Applied Math Forum
    Replies: 1
    Last Post: August 16th 2006, 11:29 AM

Search Tags


/mathhelpforum @mathhelpforum