Inclined Plane & Friction

Find the tipping point

  1. Slowly raise the ramp angle. Static friction balances the downhill component of gravity until its maximum is exceeded.
  2. Watch the block begin to slide. The friction arrow now represents kinetic friction.
  3. Return the block to the top to repeat. Compare surfaces or add mass. Pause to inspect the free body diagram.

At the onset of sliding, μₛ = tan θ. While sliding downhill, μₖ = (g sin θ − a) / (g cos θ). Use the live angle and acceleration to explore these relationships.

Dashed gravity components resolve the weight; they are not additional forces. Coefficients are illustrative, constant dry-friction values. Ramp adjustments reset the block; the hinge motor holds the chosen angle. No data are recorded.

Adjustable inclined plane

STATIC / AT REST
WOOD BLOCK · 1.20 m TRACK · ANGLE SCALELIVE APPARATUS
Wooden block on an adjustable laboratory rampA hinged wooden ramp, metal support, protractor, and moving wooden block with live force arrows. 20.0°ZORNSCIENCE / MECHANICS BENCH
Static friction balances downhill gravity.0.00 s
ACCELERATION0.00 m/s²
SPEED0.00 m/s
DISTANCE0.00 m
● Normal● Weight● Friction┄ Gravity components
Explore the physics

N = mg cos θ · W∥ = mg sin θ · fₛ ≤ μₛN · fₖ = μₖN

Adding mass increases all forces proportionally. It does not change the critical angle or sliding acceleration in this model. The block stops at a padded end stop; force arrows are hidden after impact because the stop adds a contact force.