Science: Learning about tension – How to make a toy elevator

How does an elevator lift work?

In our KiwiCo Kiwi Crate Push and Pull Toys box we learned about force and tension. When we hold a rope loosely so that it rests between us, it is slack. When we pull, that force travels along it and it becomes taut. That is tension at work. That pull force and tension can also be used to make something (or someone) move especially when we add a simple machine – like a pulley. SciShow Kids gives a great visual example of how this works: click here to watch.

An elevator lift relies upon the science of tension so that those vertical cables, a pulley, and counterweights, can create a lift force in order to move people or objects. An elevator lift’s science and internal mechanisms can make for fascinating reading and is more complex then this simple build. This craft is a great place to start for younger kids, and older kids may want to engineer their own more complex designs!

How to make a kids toy elevator lift

Our Kiwi Crate came with this great idea in the Explore magazine!

Materials

  • Sturdy cardboard box
  • Wooden dowel (cut to size)
  • String
  • Pencil, scissors, glue, sellotape, ruler.
  • Decorations

Tip: Where can I get a wooden dowel? Turns out, lots of places! Craft stores and hardware stores are a good place to start. Keep in mind that you’ll want the wooden dowel to be at least the width of your box (with some extra length each side as turning handles).

Instructions

  1. Cut the lid / flaps off the top face of the box. (Save them)
  2. You want to make a small hole for your wooden dowel. Stand your box and choose a short end to be the top of the ‘building’. Choose a ‘side’ of the building and use a ruler to measure about an inch down from the ‘roof’ and make a pencil mark. Use a sharp pencil (or scissors) to carefully push a hole through the cardboard.
  3. Slide the wooden dowel through the hole and use it (as well as your ruler) to help you position a matching hole on the far side of the ‘building’.
  4. To make your ‘elevator’, cut the cardboard that you saved into two strips. Experiment with scoring and folding these, then slide them together to make a rectangle (you’ll need to tape or glue the sides). You will need to trim them to size as if they press too closely against the building walls, friction will slow the elevator’s rise.
  5. Make two holes in the ‘roof’ of the elevator.
  6. Measure and cut your string; you want it about twice as long as your building is high.
  7. Thread string through one hole and tie a knot inside the elevator lift. Take the other end of the string and wrap it around the wooden dowel (acting as a pulley) and then place the end through the roof of the elevator and knot it off.
  8. Make sure your string has equal lengths on each side and then tape the centre of the loop to the dowel.
  9. Have fun decorating your building and elevator 🙂
  10. You are now ready to lift! Simply twist the handles and watch the elevator rise as the string wraps itself around the dowel. Observe how the lift force requires the cable (string) to retain tension in order to operate. Discuss what would happen if the string was too long and stayed like limp spaghetti. What can you lift? Are some things too big or too heavy? Do some shapes wobble and fall off? Is it the right height to transport cars or dinosaurs or dolls where they want to go? What size might you need to reach a floor in a dollhouse, or the top of a coffee table, or the seat of the couch?

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