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IB Physics is algebra-based. You need these 5 equations cold.
- Final velocityv = u + atCalculator
- Displacements = ut + ½at²Calculator
- v² relationv² = u² + 2asCalculator
- Average velocityv̄ = (u+v)/2
- Projectile rangeR = v₀² sin2θ / gCalculator
- Free fallh = ½gt² (from rest)
💪 IB Practice: A ball is dropped from rest off a 20 m cliff (g = 10 m/s²). How long does it take to hit the ground?
- A1 s
- B2 s
- C4 s
- D√10 s
- Newton's 2nd LawF_net = maDeep Dive
- WeightW = mg (g = 9.8 m/s²)
- Friction (kinetic)f = μâ‚–N
- Centripetal forceF_c = mv²/r = mω²r
- GravityF = Gm₁m₂/r²Calculator
- Normal force (incline)N = mg cosθ
💪 IB Practice: A 60 kg person stands in an elevator accelerating upward at 2 m/s². What is the normal force?
- A480 N
- B588 N
- C708 N
- D60 N
- WorkW = Fd cosθ
- Kinetic energyKE = ½mv²Calculator
- Potential energyPE = mgh
- Conservation of energyKE₁ + PE₁ = KE₂ + PE₂
- PowerP = W/t = Fv
- Spring PEPE = ½kx²
Fluids are disproportionately tested on the IB — multiple questions per exam. Master every equation here.
- Densityρ = m/V
- PressureP = F/A
- Fluid pressure (depth)P = P₀ + ρgh
- Buoyancy (Archimedes)F_b = ρ_fluid × V_submerged × g
- ContinuityA₁v₁ = A₂v₂
- Bernoulli's equationP + ½Ïv² + ρgh = constDeep Dive
- Poiseuille's LawQ = πr⁴ΔP / 8ηL
- Viscosity – flow resistanceR = 8ηL / πr⁴
- Surface tensionF = γL (force per unit length)
💪 IB Practice: A blood vessel with radius r is partially occluded to radius r/2. By what factor does flow resistance increase?
- A2×
- B4×
- C8×
- D16×
💪 IB Practice: A 200 g wooden block (density 500 kg/m³) is placed in water (1000 kg/m³). What fraction is submerged?
- A25%
- B50%
- C75%
- D100%
- First LawΔU = Q − W
- Ideal Gas LawPV = nRT (R = 8.314 J/mol·K)
- Ideal Gas Law (molecular)PV = Nk_BT
- Carnot efficiencyη = 1 − T_c/T_hCalculator
- Heat capacityQ = mcΔT
- Second LawΔS_universe ≥ 0
💪 IB Practice: A heat engine operates between 500 K and 300 K. What is its maximum efficiency?
- A40%
- B50%
- C37%
- D40%
- Ohm's LawV = IRCalculator
- PowerP = VI = I²R = V²/R
- Series resistanceR_T = R₁ + R₂ + …
- Parallel resistance1/R_T = 1/R₁ + 1/R₂ + …
- CapacitanceC = Q/V; U = ½CV²
- Coulomb's LawF = kq₁q₂/r²
- Electric fieldE = F/q = kq/r²
- Electric potentialV = kq/r
💪 IB Practice: Two 6 Ω resistors are connected in parallel. What is the equivalent resistance?
- A6 Ω
- B12 Ω
- C3 Ω
- D1 Ω
- Wave speedv = fλCalculator
- Sound speed (air 20°C)v ≈ 343 m/s
- Doppler effectf' = f × (v ± v_obs)/(v ∓ v_s)
- Intensity levelβ = 10 log(I/I₀) dB
- Standing wave (string)f_n = nv/2L
- Resonance (closed pipe)f_n = (2n−1)v/4L (odd harmonics)
- Speed of lightc = 3 × 10⁸ m/s
- Snell's Lawn₁sinθ₁ = n₂sinθ₂
- Thin lens1/f = 1/d_o + 1/d_i
- Magnificationm = −d_i/d_o = h_i/h_o
- Lens powerP = 1/f (diopters, f in metres)
- Critical anglesinθ_c = n₂/n₁
💪 IB Practice: An object is placed 30 cm in front of a convex lens with f = 10 cm. Where is the image?
- A10 cm in front of lens
- B15 cm behind lens
- C30 cm behind lens
- DAt the lens
- Radioactive decay lawN(t) = N₀(½)^(t/t½)Calculator
- Decay constantλ = ln(2) / t½
- ActivityA = λN (Becquerels)
- Mass–energy equivalenceE = mc²
- Binding energyBE = Δm × c² (mass defect)
IB radiation types: Alpha (α) = ⁴₂He — stopped by paper. Beta (β) = electrons — stopped by 1 cm Al. Gamma (γ) = photons — stopped by lead/concrete.
🧠 Full IB Physics Practice Quiz
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📚 Recommended IB Physics Books
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Frequently Asked Questions
How much physics is on the IB?
Physics topics appear primarily in the IB Exam. Approximately 25% of that section is physics — roughly 15 out of 59 questions.
What physics topics are most heavily tested?
The highest-yield topics are: Fluids (Bernoulli, Poiseuille, buoyancy), Circuits (Ohm's Law, series/parallel), Kinematics (SUVAT), and Optics (lens equation, Snell's Law).
Do I need calculus for IB physics?
No. IB Physics is entirely algebra-based. Calculus is not required. However, strong proportional reasoning (e.g. "if r doubles, F decreases by factor of 4") is essential.
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