What is a pulley and how does it work?

A pulley is a grooved wheel with a rope running around it. As you pull one end of the rope, the wheel turns and moves the load on the other end, letting you change the direction of your pull or share a heavy weight across several ropes.

Why is it easier to lift something with a pulley?

A single fixed pulley lets you pull downwards instead of lifting straight up, so you can use your body weight to help. Adding movable pulleys spreads the load across more ropes, so each rope — and your arm — carries only a fraction of the weight.

What is the difference between a fixed pulley and a movable pulley?

A fixed pulley is attached to a fixed point and only changes the direction of your force, not its size. A movable pulley travels with the load and reduces the effort needed, because two or more rope sections share the weight.

What is a block and tackle?

A block and tackle is a system of several pulleys threaded with one rope. The more rope sections that support the load, the less effort you need to lift it — though you have to pull the rope a greater distance.

Where do we see pulleys in everyday life in Singapore?

Pulleys are used on flagpoles, construction cranes, window blinds, lifts, sails, and wells. They appear anywhere people need to raise, lower, or move heavy things with less effort.

How Pulleys Lift Heavy Things

Science Interactive lesson Free to play

A pulley is a simple machine made of a wheel with a groove around its rim and a rope that runs through the groove. It changes the direction of a pulling force and, when several wheels are combined, reduces the effort needed to lift a heavy load. People use pulleys to raise flags up poles, hoist sails, operate window blinds, draw water from wells, and lift huge blocks with construction cranes.

There are two main tricks behind a pulley. A single fixed pulley lets you pull down to lift something up, which is easier because you can use your own body weight. Adding a movable pulley that travels with the load shares the weight across two ropes, so each rope carries only half — you pull with half the force but must pull twice as much rope. Combining many wheels and ropes makes a block and tackle, where more rope sections sharing the load means even less effort.

Key ideas a learner will grasp: a pulley is a wheel plus a rope, fixed pulleys change direction, movable pulleys share the load, and more supporting ropes mean less effort but a longer pull.

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A super-helper machine

🏗️🪢 How Pulleys Lift Heavy Things Have you ever seen a crane lift a giant block, or pulled a flag up a pole? They use a clever little machine called a pulley! A pulley turns a hard pull into an easy pull. 💪➡️🙂 Tap Next and let's find out how it works!
What is a pulley?

What is a pulley? A pulley is just a wheel with a groove and a rope that runs around it. Tap each part to learn its job! 🛞 Wheel 📍 Axle 🪢 Rope 👆 Tap a part above to see what it does.
Pull DOWN to lift UP

Trick 1: Change the direction A pulley fixed to the top lets you pull DOWN to make the box go UP. Pulling down is easier — you can use your own body weight! ✊ 📦 ⬇ Pull the rope down! The box is on the ground. Pull to lift it up!
Sharing the weight

Trick 2: Share the load Here is the magic! Add a second wheel that moves with the box. Now two ropes hold the weight, so each rope only carries half. You pull half as hard! 🎉 A box weighs 100. How hard do you pull with this 2-wheel pulley? 😣Pull 100(all of it) 🙂Pull 50(half!) 😮Pull 0(nothing)
More wheels = easier

Trick 3: More wheels, less effort Add even more wheels and ropes — this is called a block and tackle. The more ropes share the weight, the easier it gets. Drag the slider to add wheels! Pull strength: 100 🛞 Wheels (ropes): 1 Goal: slide it to make the pull as easy as possible. 💪
Pulleys all around us

Spot the pulleys! Pulleys are everywhere in Singapore. Tap the things that use a pulley. Watch out — one of them does not! 🚩Flagpole 🏗️Crane 🪟Window blinds 🪣Well bucket 🛝Playground slide Found 0 of 4 pulleys.
You're a pulley pro!

🏆🪢 Well done, pulley pro! You now know how pulleys lift heavy things: A pulley is a wheel + rope that helps us lift. One fixed pulley lets you pull down to lift up. A movable pulley shares the load, so you pull half as hard. More wheels = even easier lifting (block and tackle). Pulleys are real: flagpoles, cranes, blinds and wells! 🚩🏗️ Next time you raise a flag, you'll know the secret! 🎉

Frequently asked questions

What is a pulley and how does it work?: A pulley is a grooved wheel with a rope running around it. As you pull one end of the rope, the wheel turns and moves the load on the other end, letting you change the direction of your pull or share a heavy weight across several ropes.
Why is it easier to lift something with a pulley?: A single fixed pulley lets you pull downwards instead of lifting straight up, so you can use your body weight to help. Adding movable pulleys spreads the load across more ropes, so each rope — and your arm — carries only a fraction of the weight.
What is the difference between a fixed pulley and a movable pulley?: A fixed pulley is attached to a fixed point and only changes the direction of your force, not its size. A movable pulley travels with the load and reduces the effort needed, because two or more rope sections share the weight.
What is a block and tackle?: A block and tackle is a system of several pulleys threaded with one rope. The more rope sections that support the load, the less effort you need to lift it — though you have to pull the rope a greater distance.
Where do we see pulleys in everyday life in Singapore?: Pulleys are used on flagpoles, construction cranes, window blinds, lifts, sails, and wells. They appear anywhere people need to raise, lower, or move heavy things with less effort.

How Pulleys Lift Heavy Things

What this Spark covers

Frequently asked questions

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