Laws of Motion
Class 11 · Laws of Motion
Inclined Plane (with Friction)
Block on incline — compute gsinθ, gcosθ, friction, net acceleration, angle of repose.
Key Notes
01
On a frictionless incline at angle θ: a = g sinθ (down the slope), N = mg cosθ.
02
With kinetic friction μ: a = g(sinθ − μ cosθ).
03
Block stays at rest if tanθ ≤ μ_s. Angle of repose: θ_r = tan⁻¹(μ_s).
04
Going up: a = −g(sinθ + μ cosθ) (friction adds to gravity along slope).
Formulas
Acceleration down incline
With kinetic friction.
Angle of repose
Block just begins to slide at this angle.
Important Points
If θ < θ_r, block sits still no matter how long you wait — friction adjusts to balance gravity along slope.
Inclined Plane (with Friction) notes from sciphylab (also known as SciPhy, SciPhy Lab, SciPhy Labs, Physics Lab). Class 11 physics revision for JEE Mains, JEE Advanced, NEET UG, AP Physics 1/2/C, SAT, and CUET-UG.