Laws of MotionAll
Laws of Motion — Formula Sheet
Overview
All the key formulas for Laws of Motion (Class 11) on one page — with symbols, SI units and the conditions each formula applies under. NCERT-aligned for NEET & JEE.
Formula handbook — Laws of Motion
All the key Laws of Motion formulas for Class 11 Physics on one page. Use
g = 9.8 m/s² (≈ 10 m/s² when a question says so).
| Quantity | Formula | Notes |
|---|---|---|
| Linear momentum | p = m v |
vector, SI unit kg·m/s |
| Newton's second law | F = dp/dt = m a |
a in direction of net force |
| One newton | 1 N = 1 kg·m/s² |
definition of the force unit |
| Impulse | J = F Δt = Δp = m(v − u) |
area under the F–t graph |
| Conservation of momentum | m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂ |
no external force |
| Weight | W = m g |
gravitational force, acts downward |
| Apparent weight in a lift | N = m(g ± a) |
+a up, −a down; N = 0 in free fall |
| Static friction (max) | f_s(max) = μ_s N |
a range 0 ≤ f_s ≤ μ_s N |
| Kinetic friction | f_k = μ_k N |
opposes sliding, μ_k < μ_s |
| Angle of repose | tan θ = μ_s |
block just slips on an incline |
| Acceleration on a smooth incline | a = g sin θ |
along the incline |
| Centripetal force | F_c = m v²/r = m ω² r |
net inward force |
| Max speed on a level road | v_max = √(μ_s r g) |
friction supplies F_c |
| Max speed on a banked road (no friction) | v = √(r g tan θ) |
banking angle θ |
Key relations to remember
- Equilibrium ⇒
ΣF = 0(first law); non-zero net force ⇒a = ΣF / m. - Action and reaction are equal, opposite and act on different bodies.
- For connected bodies: find acceleration from the whole system, then tension from one body's FBD.