Jupiter2U School
Chapter 04

Simple Machines & How Things Move

Primary
At a glance
Core ideaA simple machine trades a smaller force over a longer distance to make a job easier.
Key termLever — a bar on a pivot; the farther from the pivot, the more lifting power.
You can…Explain why a door handle sits far from the hinge, not beside it.
Watch outMachines don't create energy — they only rearrange the effort you put in.
Theory

Machines that make work easier

You don't need batteries or motors to be a "machine" — a simple machine is just a clever shape that makes a push or pull easier. A lever (like a see-saw or a bottle opener) lets a small push at one end lift a big weight at the other. A ramp (inclined plane) lets you roll a heavy box up gradually instead of lifting it straight up. A wheel and axle (like a doorknob or a wagon wheel) turns a small twist into a bigger turning force.

Simple machines don't remove work — they trade less force over a longer distance for the same job, which is often much easier for our muscles.

Explanation

Why a longer lever lifts more easily

Push down near the far end of a see-saw and even a small push can lift a much heavier friend on the other side. Move your hands closer to the middle (the pivot point) and it gets harder to lift them. The farther your push is from the pivot, the more lifting power it has — this is why door handles sit far from the hinge, not right next to it. Try pushing a door open right next to the hinge — it's much harder than pushing at the handle.

Everyday machines. A pair of scissors is two levers joined together. A slide is a ramp. A see-saw, a wheelbarrow, and a bicycle pedal are all simple machines at work.
Practical

Try it — build a ruler lever

  1. Rest a ruler across a pencil (the pencil is the pivot) like a tiny see-saw.
  2. Place a small toy or eraser on one end.
  3. Press down gently on the other end, close to the pencil. How hard is it to lift the toy?
  4. Now press down at the very far end of the ruler, away from the pencil. Is it easier?
  5. Slide the pencil closer to the toy's end and try again. What changes?
Q&A
Name three simple machines.

Any three of: lever, ramp (inclined plane), wheel and axle, pulley, screw, wedge.

Why is it easier to push a door open at the handle than near the hinge?

The handle is farther from the pivot (the hinge), so the same push has more turning power there.

What does a ramp let you do that lifting straight up doesn't?

It lets you use a smaller push spread over a longer, gentler distance instead of one big lift.

Is a pair of scissors a simple machine? Which one?

Yes — scissors are two levers joined at a pivot (the screw in the middle).

Concept mind map

How the ideas connect

Every key idea in this chapter, branching from the core concept — use it to see the whole picture at a glance.

LeverWheel & axlePulleyRampWedgeScrewLess effortSimple Machines
Infographic

The key facts, visualised

Machine
A tool that makes work easier
Lever
A bar that turns on a pivot point
Ramp
A slope to raise loads gently
Pulley
A wheel and rope to lift loads
Solved examples

Worked problems, step by step

Follow each solution line by line, then try to reproduce it on paper before moving on.

Example 1Why is a long ruler easier to lift a book than a short one?

  1. A lever pivots on a support
  2. A longer arm gives more turning force
  3. So less push is needed

Example 2Why do movers use a ramp to load a heavy box into a truck?

  1. Lifting straight up is hard
  2. A ramp spreads the climb over a longer path
Practice problem set

Now you try

Work each one out first, then tap to reveal the worked answer.

1What simple machine is a see-saw?
A see-saw is a lever that pivots in the middle.
2Why is a screw easier than hammering a nail into wood?
A screw is a ramp wrapped around a rod, so it grips as it turns in with less force.
3How does a pulley help you raise a flag?
The pulley wheel lets you pull down while the flag goes up, which is easier.
4What machine is the sharp edge of an axe?
It is a wedge that splits wood apart.
5Where should you push on a door, near or far from the hinge?
Far from the hinge; the longer arm makes it easier to open.
6Name two simple machines on a bicycle.
The wheel and axle, and the lever brakes.