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A formula to calculate speed on loop de loop

  1. May 20, 2015 #1
    I am trying to calculate the average speed of a car while travelling around a loop de loop in m/s and km/h can any body help? Thanks
    Last edited: May 20, 2015
  2. jcsd
  3. May 20, 2015 #2
    There will be several willing to help ... only if they see some initial attempt
  4. May 20, 2015 #3
    I have been watching loop de loops on youtube and was wanting to see if I could calculate it on the hotwheels track. I worked out the minimum speed the car has to be at the top of the track to be 0.431m/s or 1.55 km/hr but calculating the average speed below , it seems too fast. Wondering if I have the formula right.

    Loop radius: 19cm. Loop Time= 0.041 secs

    Circumference = 2pi * 19cm radius = 0.038pi (meters)
    0.038pi / 0.041 secs = avg speed in m/s
    0.038pi / 0.041 = 2.91 m/s
    To convert to km/h
    2.91m/s * 3600 (seconds in hours) / 1000 (1000meters = km)
    2.91 * 3.6 = 10.5 km/h

    So the hotwheels car was traveling 2.91m/s or 10.5km/h
  5. May 20, 2015 #4
    One can use the principle of the conservation of energy to derive the required formula.
  6. May 20, 2015 #5


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    The limiting case of a car 'just' keeping on the track when at the top of the invert will be when the centripetal acceleration (v2/r ) is equal to g. (i.e. it is just in contact with the track) At the bottom, the extra KE will be the same as the gravitational potential difference between top and bottom (mgh). The total KE gives you the velocity, which will give you the effective 'g' at the bottom. Believe in the formula and apply it correctly and the numbers will be right.
  7. May 20, 2015 #6
    How do you know the time to go around the loop?
    And your minimum speed at the top sem to be off. For a radius of 19 cm should be around 1.4 m/s I believe.
    Last edited: May 20, 2015
  8. May 20, 2015 #7
    Ok thank you very much
  9. May 20, 2015 #8
    If it was, can you show me how you did the formula
  10. May 21, 2015 #9
    The formula can be obtained by using the principle of the conservation of energy... as I said earlier!
  11. May 21, 2015 #10
    So can you show me how to do the formula as I looked on the Internet of conservation of energy I didn't understand how to use it in my question
  12. May 21, 2015 #11
    thank you, yes I made an error now this is starting to make sense
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