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:S Help Again Please!

  • 08-11-2009 12:34pm
    #1
    Stephen Esquire
    Closed Accounts Posts: 61 ✭✭


    Any help again would be appreciated!


    A pole-vaulter approaches the takeoff point at a speed of 8.95 m/s. Assuming that only this speed determines the height to which he can rise, find the maximum height at which the vaulter can clear the bar.


    A sled is being pulled across a horizontal patch of snow. Friction is negligible. The pulling force points in the same direction as the sled's displacement, which is along the +x axis. As a result, the kinetic energy of the sled increases by 35.6 percent. By what percentage would the sled's kinetic energy have increased if this force had pointed 52.0 ° above the +x axis?


Comments

  • #2
    Fringe
    Registered Users, Registered Users 2 Posts: 1,082 ✭✭✭Fringe


    1) Remember the conservation of energy. The total energy of the person is 1/2mv^2 + mgh. When the person is running, their potential energy is zero and when the person reaches the maximum height, the kinetic energy is zero. The energy stays the same so equate them to get the answer.

    2) Try resolving the force into components in the x and y direction. You're only concerned with the x direction so look at that. Also, remember the definition of work: W = F.x


  • #3
    HankScorpio1985
    Registered Users, Registered Users 2 Posts: 265 ✭✭HankScorpio1985


    Fringe wrote: »
    1) Remember the conservation of energy. The total energy of the person is 1/2mv^2 + mgh. When the person is running, their potential energy is zero and when the person reaches the maximum height, the kinetic energy is zero. The energy stays the same so equate them to get the answer.

    2) Try resolving the force into components in the x and y direction. You're only concerned with the x direction so look at that. Also, remember the definition of work: W = F.x

    +1


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