Stem Challenge: Pulley Challenge

This week you will build and construct a simple pulley system called a funicular train! This pulley will test your engineering skills and will give you a real-world example of how simple machines work!

What is a simple machine?:

A pulley is a simple machine.  There are six main types of simple machine: Wheel and Axle, Wedge, Screw, Pulley, Inclined Plane, and Lever. What we are going to make with our straws and string is not an exact pulley in that it isn’t a grooved wheel with a rope.  But it does the trick.  Pulleys are used to lift heavy weights. They reduce the friction in the system making it easier to move objects. Since we will have more than one pulley, we have created a compound pulley system with your funicular train. There are more types of pulley: fixed pulley systems and movable pulley systems. Two pulleys will be working together to lift and lower the loads you put into the cups.

      • Yarn or string
      • 2 Bendy Straws
      • 2 Plastic Cups
      • Tape
    1. Time to build your pulley system! Cut the straws so they are the same length on either side of the bendy part.
    2. Cut a piece of yarn about 4-5 feet long, and thread it through both bendy straws and tie it off.  Cut off the excess yarn so the knot is small.
    3. Tape one bendy straw to the wall. (Tip: If you put it around a doorknob it will be even stronger.) Place the bendy straw on the wall the same level as your height.
    4. Next, stretch the yarn so it is tight and tape the other straw to the floor.
    5. Take one cup and tape it over the knot. (This prevents the knot from getting stuck in the straws). Take the other cup and tape it on the opposite side.
    6. Now you have your train in place!
    7. You can put a small toy into one of the cups and pull on the string to lift it up and down your train! This is also fun to do with Lego or Mega Blok building projects. It’s great for homemade doll houses as an elevator. Use your imagination!

Activity Credit: Team Cartwright