Central Perk Cafe ETM

Winter Springs High School

Image of the café from F.R.I.E.N.D.S. TV show.

Team Members: Lena L. (12th), Hannah K. (12th), Diya P. (11th), Aylah P. (12th), Carissa E. (11th)


Close-up pictures of each major step in ETM

ETM Video

Video of ETM

Energy Transfers and Explanations

  • GOAL: Our Central Perk ETM’s goal was to pour creamer into a cup of coffee, to serve a fresh cup.
  • Potential energy from the marble is converted into kinetic energy as it rolls down the ramp and into the cup.
  • The increase in weight of the cup triggers the paper clip, allowing the bolt to swing left and right.
  • The weight transfer from the bolt makes the weighted balls fall due to gravitational energy.
  • The kinetic energy of the falling weighted balls pushes the button on the dinosaur track toy, converting it to mechanical energy.
  • The push of the button triggers the potential energy-filled dinosaur car to move down the ramp with kinetic energy.
  • The dinosaur car then hits the first domino, causing potential to kinetic conversion throughout the first row of the domino chain. That chain is broken up by an action figure that swings and triggers the second domino chain.
  • The last domino in the chain is attached to a string linked to a wood blocker. Once the domino falls from gravitational energy, the blocker moves and releases the car into motion.
  • The kinetic energy of the car knocks the creamer into the cup of coffee completing the task.

  • Electrical component: The dinosaur car track toy we utilized in our ETM uses batteries of 4 volts. There is a button on the top that pulls down the integrated stopper using the electricity from the batteries. We used a stick to push down our button, which allows the dinosaur car to go through the toy sequence.


  • We picked the Coffee shop from the popular 90s TV Show F.R.I.E.N.D.S. and thought it would be fitting to make a cup of coffee for our final task. Our team members are also very fond of the show, which allowed the construction process to be more enthusiastic as jokes from the show were brought up.
  • During our planning process, we experimented with many materials and techniques for our ETM. Here is a planning sketch of our machine:
Plan sketch of ETM
  • Addition of support: In our process of building the base and backboard, we noticed that extra support needed to be added behind the peg boards and the bottom of the base. Therefore, we came up with a support system on the back of the base/board.
  • We also faced in the last few moments while recording the video of the machine working, one of our steps not completing its task. When we had tested many times before our teeter-totter was working and releasing the second pulley to set off our electrical component. But once we began recording our project while running it, the teeter-totter stopped working. So we had to begin problem-solving and thinking of ways we could fix this issue. We tried many different options from adding weight to the cup, changing the marble we used, adjusting the prongs we made on the paper clip, and adding hot glue to the paper clip and the string. And a few other options of trial and error. In the end, we added a straw to the paper clip and continued to try it that way.

3 thoughts on “Central Perk Cafe ETM

  • Great theme! Love the problem solving!

  • Nice use of a theme. The way you supported the track was inventive and the pulley was fun to watch. Good job explaining the challenges you encountered during the process.

    • Thank you so much for the awesome feedback!


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