RECOMMENDED AGE LEVEL
Recommended for ages 8 and up with adult supervision.
Learn about engineering techniques used for lifting heavy objects – even buildings! Pulleys are simple machines that can accomplish very complex tasks, while cribbing is a lifting and stabilizing process that is used not only in construction, but also in fire and rescue endeavors. Here, you will use ordinary household objects to think creatively and design your own lifting project.
Cribbing material (ie: jenga, dominos, chopsticks, cardboard, etc.)
Pulley (ie: thread bobbin, the center tube in a roll of dog waste bags, ribbon spool, etc.)
Pulley frame (ie: found objects, small dowels, legos, popsicle sticks, or other longer, sturdy material)
Pulley axle (ie: dowel, metal rod, chopstick, etc.)
Hot glue or strong tape
Heavy object to be lifted
- Construct the sturdy frame for your pulley. This frame will need to withstand force. Brace the frame by attaching it to a sturdy, stable object (wooden cigar box shown).
- A cylinder with a hole in the middle will act as your pulley. If you have a cylinder, but it has no edges to keep the string on, you can create a barrier by using glue or tape applied around the cylinder edges.
- Thread a sturdy dowel or other material through the hole to act as an axle. Use glue or tape to securely attach the axle to either side of the pulley frame.
- Once your pulley is secured, tie one end of your string around a heavy object. Try lifting it without the pulley first.
TIP: You can also place your heavy object inside of a bag or bucket with handle, making it easier to tie the string to.
- Wind the string around your pulley, and pull downwards. This should make it easier and smoother to lift.
- Next, as you raise the heavy object, insert cribbing below, layer by layer.
- How high can you make the cribbing while keeping your object stable?
- What sorts of materials do you imagine could be used for real-world cribbing?
- Add to your engineering know-how with this lesson on levers, via TedEd.