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Homework Help: Kinetic energy/circular motion problems

  1. Oct 25, 2005 #1
    hi! im currently doing more homework problems, and getting stuck on questions like these:

    (1) the only force acting on a 2kg body as it moves along the x axis is given by F=(12-2x)N where x is in m. the velocity of the body at x=2m is 5.5i m/s. what is the maximum kinetic energy attained by the body?

    KE= 1/2mv^2 ... how am i to determine velocity if 5.5i m/s.... i is a unit vector, how am i supppose to solve for MAX. kinetic energy?

    (3) if the resultant force acting on a 2kg object is equal to (3i +4j) N, what is the change in kinetic energy as the object moves from (7i-8j)m to (11i-5j)m?

    again, with vector units, how do include them in my calculations?

    (2) a split highway has a number of lanes for traffic. for traffic going in one direction, the radius for the inside of the curve is 1/2 the radius for the outside. one car, Car A, travels on the inside while another car of equal mass, car B travels at equal speed on the outside of the curve. which statement about resultant forces on the cars is correct?

    a) The force on A is four times the force on B.
    b) The force on B is half the force on A.
    c) The force on A is half the force on B.
    d) The force on B is four times the force on A.
    e) There is no net resultant force on either as long as they stay on the road while turning.

    (4) how much work is done by a person lifting a 2kg object from the bottom of a well at a constant speed of 2 m/s for 5.0 sec?

    how would the work formula apply here?

    any comments would be appreciated, the more understanding i get, the better off i am. thanks.
  2. jcsd
  3. Oct 25, 2005 #2


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    Homework Helper

    I hope this isn't too much help.
    Newton II?
    Definition of acceleration?

    How is work defined (think line integral)?

    Centripetal acceleration?

    Again, the definition of work?
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