zip line

Trajectory, speed, inertia — science!

Trajectory, speed, inertia — science!

How long does it take for this trolley to gain the speed it needs to make it to the other side of the zip line? Factors like weight, slope, gravity and friction can have an incredible impact on acceleration. Build this DIY zip line, create a hypothesis with your promising little structural engineer, and put their best guess to the test!

Zip Line

What You Need:

  • Nylon rope
  • Plastic building bricks
  • Plastic plate
  • Plastic or metal trolley (pulley mechanism)
  • Stuffed toy
  • Scissors

What You Do:

  • Build a trolley car out of plastic bricks (consider adding windows to reduce weight).
  • Once your car is big and sturdy enough to fit your toy, build a roof using long flat brick pieces, being sure to create multiple layers to reinforce your design.
  • Secure the pulley to the top of the car.
  • Determine where your trolley ride will start and tie the nylon rope to a tree.
  • Slide the pulley onto the rope and have a friend help you tie the other end at a lower point on a second tree.
  • Bring the trolley car to the top of the zip line and let it fly! Experiment with the slope of your zip line and the weight of your car to see how it affects velocity.