Pulleys
Experiment with different pulleys to lift a water bottle.
In this activity, participants will test a small single pulley, a large single pulley, a two pulley system and a 4 pulley system to lift a water bottle. Each pulley system is connected to a water bottle of equal weight. They will compare the difference in the amount of effort required to lift the bottle using each pulley system.
What You Need
- Single Pulleys of the same size (3)
- Large Single Pulley (1)
- Double Pulley (2)
- Thick string or rope
- Coloured tape
- Water bottles (4), filled with equal amounts of water
- Water bottle lids, with eye hooks and washers
- Meter sticks, with four small hooks to hang pulleys from (2)
- Hooks to attach pulley on #3 and #4 water bottles (2)
- Number labels for water bottles (1-4)
- Photo of pulley system set up (for reference)
What To Do
- To set up, duct tape the ends of the meter stick and hooks to two sturdy surfaces (i.e. desks, table, chairs, etc…).
- Assemble pulley system:
- Bottle #1 should be connected to a small single pulley.
- Bottle #2 should be connected to a larger single pulley.
- Bottle #3 should be connected to a 2 pulley system.
- Bottle #4 should be connected to a 4 pulley system.
- Let participants try to lift each water bottle using the different pulley systems.
- As a group, compare and contrast the different pulley systems. Which one was the easiest to lift? The hardest? Why?
Discovery
A pulley is a modified version of a wheel and axle. A pulley consists of a grooved wheel with a rope running over it. Pulleys help us to move objects either up and down or side to side by changing the direction of the force. For example, if you are pulling down, it lifts the object up.
There are three different types of pulleys:
- A fixed pulley is a pulley that remains stationary as the load moves up and down (i.e. flagpole).
- A movable pulley is a pulley that moves up and down with the load (i.e. water-well).
- A block and tackle has both a fixed pulley and a movable pulley (i.e. crane).
Mechanical advantage is the measurement of how much a tool or machine multiplies a force. The higher the mechanical advantage, the easier it is to do the work. Pulleys can be added together to increase the distance the load travels, which allows the force to be distributed across multiple pulleys, increasing the mechanical advantage. Increasing the size of the pulley is another way to increase mechanical advantage (just as long as the weight of the pulleys remains the same). In this activity, students should notice that it is easier to lift the bottle using the 4-pulley system rather than the double or single pulleys. This is because the 4 pulley system has the highest mechanical advantage, as the weight of the water bottle is distributed across the length of the 4 pulleys. This reduces the effort needed to lift the water bottle.
Pulleys are one of the oldest machines and played a crucial role throughout human history and in shaping our modern world. Pulleys allow us to move and lift things that are beyond our capabilities. Some applications of the pulley include water wells, elevators and construction equipment.
- This activity is great hands-on exploration for community and booth events as it does not require any reset time or consumables between participants. Volunteers may choose to have key terms and questions listed on posters to help guide participants through the activity.
- Visit this picture collection to see where pulleys can be found in our daily lives!
Web
How Stuff Works- Block and Tackle (levers and pulleys)
Encyclopaedia Britannica- Simple Machine
Explain That Stuff- Tools and Simple Machines
Macaulay, D. (1988). The Way Things Work. New York: Houghton Mifflin Company. ISBN: 0-395-42857-2
Attachments
- Playful Machines - Guide (for reference)
- Photo of Pulley Set-Up
- Pulley Task Card
What's Happening?
A pulley is a modified version of a wheel and axle. A pulley consists of a grooved wheel with a rope running over it. Pulleys help us to move objects either up and down or side to side by changing the direction of the force. For example, if you are pulling down, it lifts the object up.
There are three different types of pulleys:
- A fixed pulley is a pulley that remains stationary as the load moves up and down (i.e. flagpole).
- A movable pulley is a pulley that moves up and down with the load (i.e. water-well).
- A block and tackle has both a fixed pulley and a movable pulley (i.e. crane).
Mechanical advantage is the measurement of how much a tool or machine multiplies a force. The higher the mechanical advantage, the easier it is to do the work. Pulleys can be added together to increase the distance the load travels, which allows the force to be distributed across multiple pulleys, increasing the mechanical advantage. Increasing the size of the pulley is another way to increase mechanical advantage (just as long as the weight of the pulleys remains the same). In this activity, students should notice that it is easier to lift the bottle using the 4-pulley system rather than the double or single pulleys. This is because the 4 pulley system has the highest mechanical advantage, as the weight of the water bottle is distributed across the length of the 4 pulleys. This reduces the effort needed to lift the water bottle.
Why Does it Matter?
Pulleys are one of the oldest machines and played a crucial role throughout human history and in shaping our modern world. Pulleys allow us to move and lift things that are beyond our capabilities. Some applications of the pulley include water wells, elevators and construction equipment.
Investigate Further
- This activity is great hands-on exploration for community and booth events as it does not require any reset time or consumables between participants. Volunteers may choose to have key terms and questions listed on posters to help guide participants through the activity.
- Visit this picture collection to see where pulleys can be found in our daily lives!
Resources
Web
How Stuff Works- Block and Tackle (levers and pulleys)
Encyclopaedia Britannica- Simple Machine
Explain That Stuff- Tools and Simple Machines
Macaulay, D. (1988). The Way Things Work. New York: Houghton Mifflin Company. ISBN: 0-395-42857-2
Attachments
- Playful Machines - Guide (for reference)
- Photo of Pulley Set-Up
- Pulley Task Card