Class 9 · Class 10 · 1 page
Physics formula sheet
Every key formula from motion to light, with units, on one page. Stick it on your study wall for quick revision.
Physics formulas · Class 9 & 10
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Motion
| Speed | speed = distance ÷ time |
| Velocity | v = displacement ÷ time |
| Acceleration | a = (v − u) ÷ t m/s² |
| First equation | v = u + at |
| Second equation | s = ut + ½at² |
| Third equation | v² = u² + 2as |
Force & gravitation
| Newton's 2nd law | F = ma N |
| Momentum | p = mv kg m/s |
| Weight | W = mg |
| Gravitation | F = G m₁m₂ ÷ r² |
| Pressure | P = F ÷ A Pa |
| Density | ρ = m ÷ V kg/m³ |
Work, energy & power
| Work | W = F × s J |
| Kinetic energy | KE = ½mv² |
| Potential energy | PE = mgh |
| Power | P = W ÷ t W |
| Commercial unit | 1 kWh = 3.6 × 10⁶ J |
Electricity
| Current | I = Q ÷ t A |
| Potential difference | V = W ÷ Q V |
| Ohm's law | V = IR Ω |
| Resistivity | R = ρl ÷ A Ω m |
| Series | R = R₁ + R₂ + R₃ |
| Parallel | 1/R = 1/R₁ + 1/R₂ + 1/R₃ |
| Electric power | P = VI = I²R = V²/R |
| Heating (Joule's law) | H = I²Rt |
Light
| Mirror formula | 1/v + 1/u = 1/f |
| Mirror magnification | m = h′/h = −v/u |
| Lens formula | 1/v − 1/u = 1/f |
| Lens magnification | m = h′/h = v/u |
| Focal length (mirror) | f = R ÷ 2 |
| Power of lens | P = 1/f D, f in m |
| Refractive index | n = c ÷ v |
Waves & sound
| Wave speed | v = fλ |
| Frequency | f = 1 ÷ T Hz |
| Echo distance | 2d = v × t |
Useful values: g = 9.8 m/s² · G = 6.67 × 10⁻¹¹ N m²/kg² · speed of light c = 3 × 10⁸ m/s · speed of sound in air ≈ 343 m/s (at 20 °C) · 1 kWh = 3.6 × 10⁶ J
Sign convention for mirrors and lenses: distances are measured from the pole or optical centre; in the direction of incident light = positive. · FreeStudyKit · freestudykit.com
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Learn the ideas behind these formulas: Ohm's Law and Resistance · Force and Pressure