Lever Principle Input Form
Enter any three main values and leave one blank to solve it. Angles are measured between the force direction and the arm.
Example Data Table
| Case | Lever Class | Effort Force (N) | Load Force (N) | Effort Arm (m) | Load Arm (m) | Effort Angle | Load Angle |
|---|---|---|---|---|---|---|---|
| Bench pry bar | First | 120 | 300 | 2.50 | 1.00 | 90° | 90° |
| Wheelbarrow lift | Second | 180 | 540 | 1.80 | 0.60 | 90° | 90° |
| Tweezers action | Third | 35 | 18 | 0.05 | 0.12 | 90° | 90° |
| Angled effort test | First | 220 | 260 | 1.40 | 1.10 | 75° | 90° |
| Lab balance setup | First | 60 | 80 | 0.90 | 0.67 | 90° | 85° |
Formula Used
General torque equation: Torque = Force × Perpendicular distance
Perpendicular distance: Effective arm = Arm length × sin(angle)
Lever balance condition: Effort Force × Effort Arm × sin(Effort Angle) = Load Force × Load Arm × sin(Load Angle)
Mechanical advantage: MA = Load Force / Effort Force
Velocity ratio: VR = Effective Effort Arm / Effective Load Arm
Efficiency: Efficiency = (MA / VR) × 100
These equations let the calculator solve one missing main value, compare torques, and estimate lever performance under angled force application.
How to Use This Calculator
- Select the lever class that best matches your setup.
- Enter any three main values: effort force, load force, effort arm, and load arm.
- Leave only one of those four fields blank if you want the calculator to solve it.
- Enter effort and load angles. Use 90° for a perpendicular force.
- Set a balance tolerance for judging near-equality of torque.
- Choose force and arm units for clearer reporting.
- Press the calculate button to show the result above the form.
- Review torque, mechanical advantage, efficiency, and the graph.
- Use the CSV or PDF buttons to export the current result.
FAQs
1. What does the lever principle state?
The lever principle states that a lever balances when clockwise torque equals counterclockwise torque. Torque depends on force and perpendicular distance from the pivot.
2. Why can I leave one field blank?
The calculator rearranges the balance equation to solve one unknown main value. Enter the other three main values and the force angles.
3. Why do angles matter here?
Only the perpendicular part of a force creates turning effect. The calculator uses sin(angle) to convert arm length into effective moment arm.
4. What is mechanical advantage?
Mechanical advantage compares output load to input effort. A higher value means the lever multiplies force more effectively in that setup.
5. What is velocity ratio?
Velocity ratio compares effective effort arm to effective load arm. It describes movement tradeoff and links geometry to ideal lever performance.
6. Why might efficiency differ from 100%?
Efficiency differs when actual force ratio and geometric ratio are not identical. Friction, deformation, measurement error, or rounded inputs can change results.
7. What is balance tolerance used for?
Tolerance lets you treat very small torque differences as balanced. This is useful when measurements are approximate or rounded.
8. Which lever class should I choose?
Choose first-class when fulcrum lies between effort and load, second-class when load lies between them, and third-class when effort lies between them.