Inclined Plane Calculator
Resolve gravity and kinetic friction along a sloped surface.
Resolve forces along an incline
An inclined plane redirects part of an object's weight along the surface while the remaining component presses into it. This calculator resolves those components, computes the normal force, applies a user-supplied kinetic friction coefficient, and reports acceleration along the downhill axis. It is useful for checking mechanics exercises, estimating a sliding load, or separating force components before a more detailed simulation.
For a 10 kilogram mass on a 30 degree slope with coefficient 0.2 and gravity 9.81 meters per second squared, the normal force is 84.9571 newtons. Kinetic friction is 16.9914 newtons, leaving an acceleration of 3.20586 meters per second squared downhill. A negative acceleration means the assumed downhill motion would be slowed rather than accelerated.
Know when the sliding model applies
The equation assumes the object is already sliding and friction has constant magnitude equal to coefficient times normal force. It does not decide whether static friction initially prevents motion, and it omits rolling resistance, air drag, ropes, and changing slope angle. Inputs are evaluated locally in your browser. Use one consistent unit system and distinguish kinetic friction from the usually larger static-friction threshold.
Frequently Asked Questions
Does this calculator use static or kinetic friction?
It uses kinetic friction for an object assumed to be sliding. Static friction needs a separate maximum coefficient and a motion check.
Why can acceleration be negative?
A negative result means kinetic friction exceeds the downhill gravity component for the chosen positive direction.
What direction is the normal force?
The normal force acts perpendicular to the surface and equals mass times gravity times the cosine of the slope angle in this model.
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