Name:
Period:
Date:
Background
A simple machine helps people do work by changing the size or direction of a force. It does not create energy. Common types are levers, pulleys, wheels and axles, inclined planes, wedges, and screws.
| Machine | Main idea | Example |
|---|---|---|
| Lever | Rotates around a fulcrum | Crowbar |
| Pulley | Rope moves over a wheel | Flagpole |
| Wheel and axle | Large wheel and smaller axle rotate together | Doorknob |
| Inclined plane | Longer path reduces required force | Ramp |
| Wedge | Moving inclined plane separates material | Knife |
| Screw | Inclined plane wrapped around a cylinder | Bolt |
1. Identify the Machine
| Object | Simple machine | Input force | Output effect |
|---|---|---|---|
| Bottle opener | |||
| Wheelbarrow | |||
| Staircase | |||
| Scissors | |||
| Jar lid threads |
2. Mechanical Advantage
For an ideal lever, mechanical advantage can be estimated by:
Mechanical advantage = effort-arm length ÷ resistance-arm length
- A lever has a 60 cm effort arm and a 15 cm resistance arm. Find the ideal mechanical advantage.
- If the output force is 240 N, estimate the required ideal input force.
- A second lever has a 45 cm effort arm and 15 cm resistance arm. Which lever requires less input force?
3. Design Scenario
A maintenance team must lift a 400 N equipment cover by hand. They can use either:
- Option A: a lever with a mechanical advantage of 4
- Option B: a two-rope-support pulley with an ideal mechanical advantage of 2
Calculate the ideal input force for each option. Then identify one practical advantage and one drawback of each.
| Option | Input force | Advantage | Drawback |
|---|---|---|---|
| A | |||
| B |
4. Recommendation
Recommend a mechanism and support the choice with calculations and practical reasoning.
Submission Checklist
- All analysis questions are answered.
- Required calculations, tables, sketches, or diagrams are complete.
- The final recommendation uses evidence from the lesson.
- Your name, class period, and date are included.
Closing Reflection
What was the most important engineering or manufacturing decision you made in this lesson? Explain why it mattered.