Inclined-plane force calculator

Quasistatic upward pull with Coulomb sliding friction.

statics-inclined-plane.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

Scenario	normalN	pullN
	94.7573	44.3416
	75.8059	35.4733

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

pull budget44.34 N✓ passes

BASELINE INPUTS

mass10 kgangle15 degfriction0.2 gravity9.81 m/s^2

CALCULATED

normal94.757 N

pull44.342 N

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Inclined-plane force
# Scope: Quasistatic upward pull with Coulomb sliding friction.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

mass = 10 kg
angle = 15 deg
friction = 0.2
gravity = 9.81 m/s^2

normal := mass*gravity*cos(angle) [N]
pull := mass*gravity*sin(angle)+friction*normal [N]

check pull budget: pull <= 60 N

scenario alternative: mass = 8 kg

Calculated from your source · not saved

Baseline · Baseline

pull budget44.34 N ✓ passes

alternative · alternative

pull budget35.47 N ✓ passes

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

normal: normal = mass*gravity*cos(angle) [N]
pull: pull = mass*gravity*sin(angle)+friction*normal [N]

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

mass: 10 kg
angle: 15 deg
friction: 0.2
gravity: 9.81 m/s^2

Calculated

normal: 94.7573 N
pull: 44.3416 N

Assumptions and limits

Quasistatic upward pull with Coulomb sliding friction.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Inclined-plane force. Inputs: mass; slope; friction coefficient. Outputs: push or pull force; normal reaction. Model scope: Rigid-body, quasistatic equilibrium. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

Inputs: mass, slope, friction coefficient
Outputs: push or pull force, normal reaction
Modes: calculate, compare, sweep
Drawing: Free-body diagram

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS