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Help Can Someone Solve This Simple Physics Problem For Me?

  1. Oct 8, 2004 #1
    Help!!! Can Someone Solve This Simple Physics Problem For Me??

    hi i need help with a homework problem for physics: it goes like this:

    A roller coaster car of mass 310 kg (including passengers) travels around a horizontal curve of radius 40 m. Its speed is 18 m/s. What is the magnitude and direction of the total force exerted on the car by the track?

    _______N at _______° above the horizontal.


    The first answer I tried was calculating the normal force exerted by the track (which was simply mass * gravity, and 90 degrees above the horizontal). That was wrong. Then I tried giving the answer as the centripetal acceleration ((m * V^2)/ r), and the angle as 0 degrees above the horizontal. That was wrong too.

    So how do I solve this and what are the answers?????????? Does anyone know, please help?!!!
  2. jcsd
  3. Oct 8, 2004 #2


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    Well, how about accounting for both gravity and cetripetal acceleration at the same time? Also, the force that the car exerts on the track (rather than the force the track exerts on the car) is what the problem is asking for.
  4. Oct 8, 2004 #3

    Doc Al

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    Staff: Mentor

  5. Oct 8, 2004 #4
    Posted by the same person too
  6. Oct 8, 2004 #5
    Ok, so if i understand it right:

    Take the normal force (which is the same as gravity * mass) and say that it acts in the vertical direction. Then take the centripetal force as (v^2 * m)/r. Then add these two vectors together????

    Can someone please be straightforward about this problem's solution or very clear on how to find it (give the equations) lol???
  7. Oct 8, 2004 #6


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    Homework Helper

    Think in components!!!!!!!!! [The Second Biggest Hint after everyone :rofl: ]
  8. Oct 8, 2004 #7
    lol Im trying to think in components

    This problem's due in 30 mins so someone please solve it for me or at least give the equations and how to get the angle (I know its really simple, its just that I have one attempt left to get it right, ive already used up four attempts, so i wanna be sure i get it right).
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