Welcome!
Hi! This guide will help you learn everything you need for the Simple Machines event. You and your partner will take a written test plus an optional lever lab.
What you'll learn
- The 6 simple machines and their parts
- How to identify simple machines in everyday objects
- Forces, free body diagrams, and net force
- Newton's 3 Laws of Motion
- How energy gets passed around
- Mechanical Advantage: IMA, AMA, and Efficiency
What is NOT on the test
- Calculus
- Quantitative air resistance
- History of mechanical systems
- Quantitative analysis of energy
- Compound machines with more than 2 simple machines
How to use this guide
- Read each machine section (top nav buttons)
- Play the games: Match It, Lever Detective, FBD Builder, Pulley Counter, Newton's Laws
- Test yourself with the Identify Practice and Big Quiz
- Practice the lab on the Lever Lab page
The 6 Simple Machines
Click any machine to jump to that section:
Lever Class 1, 2, 3
A lever is a stiff bar that pivots around a fixed point called the fulcrum. You push on one end (the effort), and that lifts or moves a load at the other end.
The three parts
- Fulcrum (F): the pivot point
- Effort (E): the force you apply
- Load (L): the weight you are moving
The three classes
The class of a lever depends on the order of F, E, and L along the bar.
Class 1: F in middle
Order: L โ F โ E
Examples: seesaw ๐, scissors โ๏ธ, crowbar, pliers, hammer claw pulling a nail ๐จ
Class 2: L in middle
Order: F โ L โ E
Examples: wheelbarrow, nutcracker, bottle opener ๐พ, doors ๐ช
Class 3: E in middle
Order: F โ E โ L
Examples: tweezers, fishing rod ๐ฃ, baseball bat โพ, broom ๐งน, your forearm ๐ช
Class 1 โ Fulcrum in middle
Class 2 โ Load in middle
Class 3 โ Effort in middle
Mechanical Advantage of a Lever
The effort arm is the distance from the fulcrum to where you push. The load arm is the distance from the fulcrum to the load.
If your effort arm is longer than the load arm, you don't need as much force. That's why a crowbar makes lifting easier!
IMA = 60 รท 10 = 6. You can lift 6ร more weight than the force you push with!
Class summary table
| Class | Middle | IMA | Trade-off |
|---|---|---|---|
| 1 | Fulcrum | Can be >1, =1, or <1 | Depends on arm lengths |
| 2 | Load | Always > 1 | Less force, but slower motion |
| 3 | Effort | Always < 1 | More force needed, but faster motion |
๐งฎ Try it: Lever IMA calculator
โก Mini Quiz: Levers
Inclined Plane
An inclined plane is a flat, slanted surface โ basically a ramp. It lets you raise something heavy by pushing it up the slope instead of lifting straight up.
Two key measurements
- Length (L): how long the slope is
- Height (h): how tall the ramp is
IMA = 6 รท 2 = 3. You push with 1/3 the force, but you push 3ร the distance.
Examples in the real world
โฟ Wheelchair ramps, ๐ slides, ๐ช stairs (a series of small inclined planes), ๐ฃ๏ธ highway exit ramps, ๐ loading dock ramps.
๐งฎ Try it: Ramp IMA calculator
โก Mini Quiz: Inclined Plane
Pulley
A pulley is a wheel with a groove that a rope rides in. Pulling on the rope changes the direction (or amount) of force needed to lift a load.
Three types
Fixed Pulley
IMA = 1
Changes direction of force. Pull DOWN to lift UP.
Examples: flagpole ๐ฉ, window blinds
Movable Pulley
IMA = 2
The pulley moves WITH the load. Half the force, but pull twice as far.
Examples: construction crane hook
Compound (Block & Tackle)
IMA = number of rope segments holding the load
Combines fixed + movable pulleys.
Examples: sailboats โต, gym weight machines, elevators ๐
๐งฎ Try it: Pulley IMA
โก Mini Quiz: Pulley
Wheel and Axle
A wheel and axle is a large wheel attached to a smaller rod (the axle). When the wheel turns, the axle turns too โ a small force on the wheel becomes a strong twist on the axle.
IMA = 4 รท 1 = 4. A small twist on the knob = 4ร the turning force on the latch.
Examples
- ๐ช Doorknob (wheel = knob, axle = rod inside)
- ๐ Steering wheel
- ๐ช Screwdriver (handle = wheel, shaft = axle)
- ๐ฐ Faucet handle
- ๐ก Ferris wheel
- ๐ฒ Car or bicycle wheels (axle drives wheel for speed and distance)
๐งฎ Try it
โก Mini Quiz: Wheel & Axle
Wedge
A wedge is like a moving inclined plane. Instead of an object sliding up a ramp, the wedge itself moves and pushes things apart. Wedges cut, split, or hold.
Two measurements
- Length (L): how long the wedge is (slope side)
- Width (W): how thick the back is
A longer, thinner wedge has a higher IMA โ easier to push in. That's why sharp knives cut better than dull ones!
Examples
- ๐ช Knife (cuts food)
- ๐ช Axe (splits wood)
- โ๏ธ Chisel
- ๐ Snowplow blade
- ๐ช Doorstop
- ๐ฆท Your front teeth!
- ๐ Nails, pins, tacks (the pointy end is a wedge)
๐งฎ Try it
โก Mini Quiz: Wedge
Screw
A screw is an inclined plane wrapped around a cylinder. Each turn of the screw moves it a little bit forward.
Key terms
- Threads: the spiral ridges
- Pitch: the distance between two threads (how far it moves in one turn)
- Circumference: distance around the screw = 2 ร ฯ ร radius
Threads that are closer together = higher IMA = easier to turn (but takes more turns).
Examples
- ๐ฉ Wood and metal screws
- ๐ก Light bulb base
- ๐ซ Jar lids
- ๐ฅค Bottle caps
- ๐ Spiral staircase
- ๐พ Corkscrew
- ๐ช Drill bit
- ๐ง Bolts and nuts
โก Mini Quiz: Screw
Forces & Newton's Laws
What is a force?
A force is a push or a pull. Forces have a size (how strong) and a direction (which way). We draw forces as arrows.
- Longer arrow = bigger force
- Arrow points in the direction of the force
Forces are measured in Newtons (N).
Common forces you'll see
- ๐ Gravity (weight): always points DOWN
- โฌ๏ธ Normal force: a surface pushing UP (perpendicular to surface)
- ๐ Applied force: a push or pull from a person or object
- ๐ Friction: opposes motion; opposite to direction of sliding
- ๐งต Tension: the pull along a rope or string
- ๐จ Air resistance: opposes motion through air
Free Body Diagrams (FBD)
A free body diagram shows all the forces acting on ONE object. Draw the object as a box or dot, then draw arrows for every force.
Example: A book sitting on a table ๐
The book isn't moving, so the forces must cancel out. Gravity pulls down with the same strength that the table pushes up.
Net Force
The net force is the total force after adding all forces together (with direction).
- Forces in the same direction โ add them
- Forces in opposite directions โ subtract them
- If net force = 0 โ object stays still OR moves at steady speed (equilibrium!)
- If net force is NOT 0 โ object speeds up, slows down, or changes direction
Now one pulls right with 10 N and the other pulls left with 6 N. Net = 4 N right.
Newton's 3 Laws of Motion
1st Law: Inertia
An object at rest stays at rest, and an object in motion keeps moving in a straight line โ unless a force acts on it.
That's why your body lurches forward when a car suddenly stops!
2nd Law: F = m ร a
The harder you push (Force), the more an object accelerates. The heavier it is (mass), the slower it accelerates.
It's easier to push an empty grocery cart than a full one.
3rd Law: Action-Reaction
For every action, there is an equal and opposite reaction.
You jump (push down on Earth), Earth pushes you up. A rocket pushes hot gas down; gas pushes rocket up.
Qualitative Energy Transfer
Energy isn't created or destroyed โ it just moves around or changes form. In a simple machine, you put energy IN, and the machine passes it to the load.
Some energy is always lost as heat due to friction. That's why machines are never 100% efficient.
- Your muscles use chemical energy ๐
- That becomes kinetic energy (the box moves) ๐ฆ๐จ
- And turns into gravitational potential energy (the box is higher) โฌ๏ธ
- A little is lost as heat from friction ๐ฅ
โก Mini Quiz: Forces & Newton
Mechanical Advantage
What is mechanical advantage?
Mechanical advantage (MA) tells you how much a simple machine multiplies your force.
- MA = 4 โ machine outputs 4ร the force you put in
- MA = 1 โ just changes direction, not force
- MA < 1 โ more force in, less out (you get more SPEED or DISTANCE instead)
IMA vs AMA
Ideal Mechanical Advantage (IMA)
What MA would be without friction. Calculated from measurements (lengths, radii).
Actual Mechanical Advantage (AMA)
What MA actually is in real life (always less because of friction).
(or: load รท effort)
IMA formulas for each machine
| Machine | IMA formula |
|---|---|
| Lever | effort arm รท load arm |
| Inclined plane | length รท height |
| Fixed pulley | 1 |
| Movable pulley | 2 |
| Compound pulley | # rope segments holding the load |
| Wheel & axle | radius of wheel รท radius of axle |
| Wedge | length รท width |
| Screw | circumference รท pitch |
Efficiency
Efficiency tells you what fraction of input energy actually does useful work.
A perfect machine would have 100% efficiency, but no real machine does because of friction.
Efficiency = (4 รท 5) ร 100% = 80%. 20% of energy was lost to friction and heat.
๐งฎ Try it: Efficiency calculator
โก Mini Quiz: Mechanical Advantage
๐ Identify the Simple Machine
Look at the picture and pick which simple machine(s) it uses.
๐ฏ Match It! Drag & Drop Game
Drag each everyday object from the left side to its simple machine on the right.
Tip on a tablet: tap and hold to drag.
Objects
Simple Machines
๐ต๏ธ Lever Class Detective
Look at the lever drawing. Where is the fulcrum (F), the load (L), and the effort (E)? Use the "FLE 1-2-3" rule to figure out the class!
๐ชข Pulley Rope Counter
Count the rope segments that support the load. That count IS the IMA!
๐ Newton's Law Scenarios
Read each scenario. Which of Newton's 3 laws does it best show?
๐ Free Body Diagram Builder
Pick a scenario, then click the force buttons to add arrows. Try to add only the forces that are actually present!
๐ Practice Test (Real Exam Style)
This is a real-style practice test, just like what you'll see in the competition. It has multiple choice, diagram, and numerical problems.
Click answers for multiple choice, type numbers for math problems, and tap "Show answer" on the longer questions.
Score: 0 / 0
1. Scissors
A pair of scissors is an example of which type of simple machine combination?
2. Identify this lever
Look at the simple machine shown below. Which type of machine is it?
3. Which is NOT a simple machine?
4. Identify this object
Which simple machine is this most closely related to?
5. Soccer ball at rest
Which of Newton's three laws best explains why a soccer ball stays at rest on the grass until someone kicks it? โฝ
6. Why is AMA < IMA?
What is the main reason the AMA of a real machine is usually less than its IMA?
7. Identify this pulley setup
The machine shown is being used to lift a load by pulling down on the rope. What kind of machine is this?
8. Box at constant speed
A student pushes a heavy box across the floor at constant speed. What is the net force on the box?
9. Lever Diagram
a) What class lever is this? How can you tell?
Show answer
Class 1 lever. The fulcrum is between the load and the effort (L-F-E pattern).
b) How long is the effort arm, and how long is the load arm?
Show answer
Effort arm = 60 cm (fulcrum to effort), Load arm = 20 cm (fulcrum to load).
c) How much effort force balances the 30 N load? (Use load ร load arm = effort ร effort arm)
Show work
30 ร 20 = E ร 60 โ E = 600 รท 60 = 10 N
d) Without changing anything else, how could you INCREASE the mechanical advantage?
Show answer
Make the effort arm longer OR make the load arm shorter (move the fulcrum closer to the load). IMA = effort arm รท load arm โ increasing the top OR decreasing the bottom raises the ratio.
10. Inclined Plane
a) What is the purpose of this simple machine?
Show answer
To lift a heavy object to a higher place using less force (you push over a longer distance instead of lifting straight up).
b) Write the IMA formula for an inclined plane and calculate the IMA for this ramp.
Show work
IMA = length รท height = 120 รท 30 = 4
c) How would you change this ramp to make it EASIER to push the 60 N box up to the same height?
Show answer
Make the ramp longer (gentler slope). Same height รท longer length = higher IMA = less force needed.
d) If you made the ramp steeper, how would that change the force needed?
Show answer
Steeper means the length stays similar but height grows โ IMA goes DOWN โ you need more force to push the box up.
11. Pulley System (Load = 40 N)
Two rope segments support the movable pulley.
a) What is the IMA?
Show work
2 rope segments support the load, so IMA = 2.
b) Minimum force needed to lift the 40 N weight?
Show work
F = Load รท IMA = 40 รท 2 = 20 N
c) In real life, you'd need MORE force. Why?
Show answer
Friction between the rope and the pulleys (and inside the pulley bearings) makes the system less than 100% efficient. Some energy is lost as heat.
d) How far would you pull the rope to raise the weight 10 cm? Give a real-life example.
Show answer
You'd pull 2 ร 10 cm = 20 cm of rope (trade more distance for less force). Real examples: construction cranes ๐๏ธ, sailboat rigging โต, elevators ๐, gym weight machines.
12. Wheel and Axle
a) What simple machine is this? Where is the effort, and where is the load?
Show answer
Wheel and axle. Effort is on the wheel (the outer rim, where the arrow is). Load is on the axle (the inner shaft, where the weight hangs).
b) IMA formula?
Show answer
c) Calculate the IMA.
Show work
20 รท 4 = 5
d) Give three real-life examples.
Show answer
Doorknob ๐ช, steering wheel ๐, screwdriver ๐ช, faucet handle ๐ฐ, Ferris wheel ๐ก, pizza cutter ๐.
13. Screw (Pitch = 0.2 cm)
a) What simple machine is the screw most closely related to?
Show answer
An inclined plane wrapped around a cylinder. The threads form a spiral ramp.
b) How many full turns to drive this screw 1 cm into wood?
Show work
1 cm รท 0.2 cm per turn = 5 turns
c) What's the advantage of needing many turns to move a small distance?
Show answer
You need much less force per turn. You trade more turns (distance) for less force.
d) Three real-life examples of screws.
Show answer
Wood screws ๐ฉ, jar lids ๐ซ, light bulb bases ๐ก, bottle caps, drill bits ๐ช, spiral staircases ๐, corkscrews ๐พ.
14. Wedge
a) What simple machine is this and what is its purpose?
Show answer
Wedge. Purpose: to split, cut, or push apart material by turning a downward push into sideways force.
b) Give one real-life example of a wedge (different from the picture).
Show answer
Knife ๐ช, axe ๐ช, chisel, nail ๐, doorstop ๐ช, snowplow blade ๐, your front teeth ๐ฆท.
c) How is a wedge similar to and different from an inclined plane?
Show answer
Similar: Both have a slanted (slope) surface. Different: An inclined plane stays still while objects slide UP it. A wedge moves INTO an object to push it apart.
d) A wedge can be made by combining which TWO simpler shapes?
Show answer
Two inclined planes placed back-to-back (sloping in opposite directions).
15. Acceleration (F = m ร a)
A shopping cart with mass 12 kg is pushed with a net force of 24 N. What is the acceleration?
Show work
a = F รท m = 24 รท 12 = 2 m/sยฒ
16. Lever IMA
A first-class lever has effort arm 80 cm and load arm 20 cm. IMA?
Show work
80 รท 20 = 4
17. Ramp IMA
A ramp is 6.0 m long and rises to 1.5 m. IMA?
Show work
6.0 รท 1.5 = 4
18. AMA of a Pulley System
A worker lifts a 600 N crate by pulling with 150 N. AMA?
Show work
AMA = load รท effort = 600 รท 150 = 4
19. Efficiency
A machine has IMA = 8 and AMA = 6. Efficiency (%)?
Show work
(6 รท 8) ร 100% = 75%
20. Net Force on a Sled
A sled is pulled right with 50 N. Friction pulls back left with 18 N. Net force?
Show work
50 โ 18 = 32 N to the right
21. Inclined Plane (60 cm, 15 cm)
a) IMA?
Show work
60 รท 15 = 4
b) Minimum force to move a 90 N box up (ignoring friction)?
Show work
F = 90 รท 4 = 22.5 N
22. Bob's Ramp (Work & Efficiency)
Bob pushes a 200 N box up a 3.0 m ramp to a height of 1.2 m with a force of 100 N.
a) Input work (Joules)?
Show work
Work = force ร distance = 100 ร 3.0 = 300 J
b) Useful output work?
Show work
Output = weight ร height = 200 ร 1.2 = 240 J
c) Efficiency (%)?
Show work
(240 รท 300) ร 100% = 80%
๐ Big Quiz
Test yourself on everything! Click an answer for each question.
Score: 0 / 0
โ๏ธ Lever Lab: Balance the Lever
In the practical part of the competition, you might have to balance a lever. A lever balances when the torque on each side is equal:
Weight ร distance from the fulcrum on the left = weight ร distance on the right.
๐ฎ Try the simulator
Use the sliders below. The lever balances when both sides have the same weight ร distance.
Weight (kg): 10
Distance from fulcrum: 6
Weight (kg): 6
Distance from fulcrum: 10
๐ฏ Goal: make Left weight ร Left distance EQUAL to Right weight ร Right distance.
๐ Practice Problems
Problem 1: A 10 kg block sits 3 m from the fulcrum on the left. Where do you put a 6 kg block on the right to balance it?
Show answer
10 ร 3 = 30 on the left. Right needs 30 too. 30 รท 6 = 5 meters.
Problem 2: A seesaw has a 40 kg child 2 m from the fulcrum. How heavy must a child be sitting 4 m away on the other side?
Show answer
40 ร 2 = 80. Other side: 80 รท 4 = 20 kg.
Problem 3: Two 5 kg masses are placed at 3 m and 6 m on the right side of a fulcrum. What single mass at 4 m on the left would balance them?
Show answer
Right side: (5 ร 3) + (5 ร 6) = 15 + 30 = 45. Left: 45 รท 4 = 11.25 kg.
Problem 4: A lever has a load arm of 0.5 m and an effort arm of 2 m. What is the IMA?
Show answer
IMA = effort arm / load arm = 2 / 0.5 = 4.
Problem 5: A 30 kg load sits 1 m from the fulcrum. The effort is applied 3 m from the fulcrum. How much effort force is needed (in kg-force) to lift it?
Show answer
Load ร Load arm = Effort ร Effort arm โ 30 ร 1 = E ร 3 โ E = 10 kg-force.