كيفية الحساب الاحتكاك القوة (Ff = μN): Static & Kinetic
احسب friction with Ff = μN. Static vs kinetic μ, normal force on ramps, worked examples, and a free friction calculator.
What الاحتكاك Asks
الاحتكاك is the force that opposes sliding between two surfaces in contact. In intro physics it is modeled as proportional to how hard the surfaces press together — the normal force N — not directly to weight unless N happens to equal mg.
The core formula is Ff = μN. μ (mu) is the coefficient of friction, a dimensionless number that depends on the materials. N is in newtons; Ff is in newtons.
If you have μ and N (or need to find one unknown), open the free friction calculator first, then return here for static vs kinetic and ramp traps.
Static vs Kinetic الاحتكاك
الاحتكاك points opposite the sliding direction or the tendency to slide.
القوة العمودية First
Ff = μN requires the correct N.
Find N with the normal force calculator before you plug into Ff = μN.
On a ramp, combine with inclined plane rules: a = g(sinθ − μk cosθ) sliding down, and μs ≥ tanθ to stay at rest.
Rearrangements
الشغلed Examples
Example 1: 10 kg box, μk = 0.40 on a floor
N = mg = 10 × 9.8 = 98 N. Ff = 0.40 × 98 = 39.2 N opposite motion.
Example 2: find μ
Measured Ff = 25 N with N = 100 N. μ = 25/100 = 0.25.
Example 3: 5.0 kg on a 30° ramp, μk = 0.20
N = mg cos(30°) = 49 × 0.866 ≈ 42.4 N. Ff = 0.20 × 42.4 ≈ 8.5 N up the ramp.
أخطاء شائعة
Check It on the Calculator
الاحتكاك calculator — Ff = μN.
Learn Ff = μN and confirm every dynamics homework number on the calculator.