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Gravity Groove

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Roller coaster design is a science, as well as an art: the designer must use knowledge of kinematics and engineering skills to create an adrenaline pumping yet safe ride. Gone are the days of steel and wooden rides so choose your material to make your experience. That's what makes the next true coaster, the one that captures the imagination.


Disclaimer: Techfest is solely responsible for all the thrill.


1. Problem Statement

Design your dream roller coaster ride.


Roller Coaster Definition: Roller coasters are called "gravity rides" for a good reason: once the coaster has been dragged to the top of the first hill and released, it is the force of gravity that keeps the coaster going, all the way back to the station platform at the end of the ride. As the coaster goes through its twists, turns, rolls and loops, it gains and loses its initial potential energy (supplied by dragging it up the first hill). Energy changes from potential into kinetic energy and back into potential energy. Since some of this initial energy is lost due to friction, the roller coaster can never rise as high as the first hill. The roller coaster you will design is also a "gravity ride".


Prizes worth INR 18,000 to be won.


View the Design Specifications »


Registration for Gravity Groove has started. Click here to register.


To view the discussions on this competition, Click here.

For further queries contact:


Agyeya Sharma

Manager, Dimensions
Techfest 2009
+91 98199 02815
agyeya[at]techfest[dot]org

Sidharth Mishra

Manager, Dimensions
Techfest 2009
+91 98198 14256
sidharthmishra[at]techfest[dot]org

2.1 Design Constraints

  1. The base must fit within a square footprint that is 750 mm x 750 mm. The overall track must fit within a rectangular box 750 mm x 750 mm x 1000 mm.
  2. The model should be designed for a steel ball or glass marble. This means that the steel ball or glass marble, when released from the top of the first hill by the judge, will travel through the entire ride and arrive at the bottom loading platform. (Note: for this contest, you will raise the steel ball or glass marble by hand from the loading platform to the top of the first hill to start the "ride").
  3. A ball must be provided by the team, so that it can be tested on the judging day. The ball must either be a glass marble of regular size, or a steel ball that is 10 mm diameter or greater.
  4. The maximum length of any straight horizontal section of track should be 200 mm.
  5. The roller coaster must have a minimum of 2 horizontal 360 degree loops and 1 vertical loop.

2.2 Materials to be used

  1. The primary construction material may be wood.
  2. Other suggested materials include wire, string, twine, doweling, toothpicks, pipe, cardboard, construction paper, popsicle sticks, glue and other cheap, easily available materials.
  3. Commercially available roller coaster kits will be disqualified.
  4. Magnets, electricity, springs and other forms of energy may not be used - this is a "gravity ride" only.

View the Rules »



3.1 Judging Criteria

The judging would include

  1. Objective score
  2. Creative score

Objective score

Objective score includes:

  1. Time factor:
    • Total time of travel starts when you leave the marble from top.
    • One point will be awarded for every two seconds.
    • The maximum time score allowed is 30 i.e. a run of 60 seconds :- if the time is less than 60 seconds then the time score is the (recorded time/2) ; if the time is between 60 and 75 seconds then the time score will be 30 (no penalty); if the time is more than 75 seconds then the time score will be 30 MINUS the (amount of time greater than 75 seconds/2) (for example if your time is 90 seconds then your time score will be 30 - (90 - 75)/2 = 22.5).

  2. Loop factor:
    • For a loop to be considered a vertical loop, the angle of the loop with respect to the vertical must be less than 15 degrees.
    • The diameter of each of the vertical loops will be measured. For loops that are not circular, diameter at the LARGEST spot will be recorded ( diameter of the largest spot signifies the maximum distance between 2 points on the loop ). The loop factor score will be equal to the diameter of circle.
    • If the vertical loop is open (so that the steel ball or marble would fall out, if it was moving too slowly) on the inner side, then the diameter that is measured would be multiplied by 2. Example: A closed loop of 100 mm diameter will get 10 points where as an open one will be awarded 20 points.

      Figure 1


    • A corkscrew is a special type of a vertical loop. Each complete revolution of 360 degrees will count as one complete vertical loop.

  3. Vertical fall factor:
    • The longest vertical fall of the ride will be measured. This measurement would be the vertical height and not the length of the track.
    • The vertical fall must make an angle greater than 60 degree with the horizontal.
    • The points for the vertical fall would be -> fall in meters x 50. Example 300 mm fall will fetch 15 points.
    NOTE: Vertical fall factor comprises only the longest fall, and not all the falls.

  4. In order to receive an objective score the steel ball or marble must complete the entire "ride" in at least 1 out of 3 trials when tested by the judging team.
  5. Total of the objective score will be the addition of the time factor + loop factor + vertical fall factor.

Creative Score

Creative score includes:

  1. Innovative engineering (15 points)
  2. Innovative material use (10 points)
  3. High g-force (5 points)
  4. Unusual thrills (5 points)
  5. Physical attractiveness and fabrication (5 points)
  6. Explanation of the design and reasoning behind the use of materials, sequence of ride, shape and structure (10 points)

The creative score would be given by judges and it will be subjective. Judges decision will be held final.


The total score of the team will be the addition of the objective score and creative score. The team with maximum total score wins.


3.2 General Rules

  1. The teams must adhere to the spirit of healthy competition. The teams must not damage the opponent's roller coaster in any way. Judges reserve the right to disqualify any team indulging in misbehaviour.
  2. Teams will be given time for the setup of their roller coaster. Any team that is not ready after the specified time will be disqualified from the competition automatically.
  3. Judges decision shall be treated as final and binding on all.
  4. The organizers reserve all rights to change any or all of the above rules as they deem fit. Change in any rule, if any, will be highlighted on the website.

3.3 Team Specifications

A team may consist of a maximum of 3 members. Students from different educational institutes can form a team.


3.4 Eligibility

All students with a valid identity card of their respective educational institutes are eligible to participate in Gravity Groove at Techfest 2009.


3.5 Certificate Policy

  1. Certificate of Excellence will be given to the top teams emerging from this competition.
  2. Certificate of Participation will be given to all the teams which score a Creative Score of atleast 20 and Objective Score of atleast 50.

3.6 Registrations

Registration for Gravity Groove has started. Click here to register.


3.7 Accommodation

  • Due to the limited accommodation facilities, teams will be short listed for accommodation based on the following abstract provided by the team. Please note that even if your abstract does not get short listed, you are still eligible to participate in the competition.
  • All participants who want accommodation at IIT Bombay during Techfest should fill the abstract form and rename the .doc file as "<Team_no>.doc" and email the form to groove[at]techfest[dot]org. The abstract should reach us latest by 2359 hrs on 15th December 2008. No more requests for accommodation will be entertained thereafter.
  • Click here to download the abstract format.
  • Accommodation registrations have started. To register for accommodation, click here.

3.8 Important dates

  1. Last date for registration for participant who don't require accommodation at IIT Bombay is 25th December, 2008. Participants need not send the abstract if they don't want the accommodation.
  2. Last date for submitting the abstract for participants who require accommodation at IIT Bombay is 15th December, 2008.
  3. Last date of registrations for the participants who wish to avail accommodation at IIT Bombay is 15th December, 2008.

View the Resources »