Simple machines make up almost all mechanical systems. They make tasks easier, because the effort is spread over a longer distance – that way less force needs to be applied by you! Pulleys are a kind of simple machine that can be found in systems like elevators, drawbridges, and construction cranes. 

In this project created by Emma, a member of the Rosie Innovators STEM program for young women in high school, you’ll be building your own pulley system to lift pennies. When pulleys have more fulcrums, or points where the string turns, it is easier to lift things. Other levers also have fulcrums, like the point where the board balances on seesaws! It would be very difficult to lift someone on the opposite end of a long board, but by placing a fulcrum in the middle, it is easy to make them go up and down.

Ready to make this project at home or in your classroom? Gather the materials listed at the right, and follow the instructions below!

Required Materials

  • 3 plastic bobbins or spools
  • 1 piece of cardboard (cereal boxes work well!)
  • 3 x the length of the cardboard string
  • easel (optional)
  • double sided adhesive
  • hole punch
  • mini paper cup
  • 10 pennies or other small weights

Step-By-Step Instructions

Step 1

Take three pieces of tape or three dots of hot glue and stick them to the cardboard piece in the shape of an upside-down triangle. They should be at least three inches apart.

Step 2

Stick the flat side of one bobbin to each piece of tape or dot of glue.

Step 3

Punch a hole in each side of the mini cup and run the string through it. Tie one end of the string to the other side just above the cup. 

Step 4

Run the string through the bobbins, starting with the one furthest to the left. The pattern is over, under, over. 

Step 5

Place the cardboard on the easel for stability (optional).

Step 6

Fill the cup with pennies, and pull gently on the end of the string to lift the cup!

Step 7

Experiment with different routes for the string through the bobbins to see if you can make a new pulley system!

Step 8

Note: Friction is a force that works against the direction of an object moving against something else. When objects rub together, it slows the motion down. You might notice that when your cup has more pennies in it (i.e., more weight), it’s harder to lift even with the pulley, because the string is creating more friction with the bobbins. Different kinds of string create more or less friction–try using different types and see what happens!

Real Women in STEM

Resource 1

Vanessa Galvez

Not all influential engineers build technologies for spacecrafts. Some, like Vanessa Galvez, have made an out-of-this-world impact in their own communities! Galvez is a civil engineer who became interested in engineering after watching a documentary about levees that stopped working during Hurricane Katrina. As a kid, she loved taking things apart and putting them together. At age 26, she led a project installing bioswales in Queens, NY. Bioswales help absorb stormwater runoff and protect the city from pollution and flooding. Galvez’s work can provide a blueprint for future urban-improvement projects, protecting the environment for generations to come.

Resource 2

This project was created by Emma, a sophomore at Washington-Liberty High School. Emma has loved STEM since she was little, because she enjoys figuring out what makes things work, from plants to airplanes to humans. According to Emma, “If we understand the world more deeply, then we can come up with better solutions to our problems!” She’s most passionate about environmental science, but is always up for learning about something new.