What are the 20 formulas in physics?

It's impossible to provide a definitive list of the 20 most important formulas in physics, as importance varies greatly depending on the specific area of study. However, here's a list of 20 fundamental formulas spanning various branches of physics. This selection represents key relationships and principles.

1. Newton's Second Law of Motion: F = ma (Force equals mass times acceleration)

2. Work Done: W = Fdcosθ (Work equals force times distance times the cosine of the angle between them)

3. Kinetic Energy: KE = (1/2)mv² (Kinetic energy equals one-half times mass times velocity squared)

4. Potential Energy (Gravitational): PE = mgh (Potential energy equals mass times the acceleration due to gravity times height)

5. Power: P = W/t (Power equals work done divided by time)

6. Ohm's Law: V = IR (Voltage equals current times resistance)

7. Electric Power: P = IV (Power equals current times voltage)

8. Wave Speed: v = fλ (Wave speed equals frequency times wavelength)

9. Refractive Index: n = c/v (Refractive index equals the speed of light in a vacuum divided by the speed of light in the medium)

10. Snell's Law: n₁sinθ₁ = n₂sinθ₂ (Relates the angles of incidence and refraction to the refractive indices of the two media)

11. Ideal Gas Law: PV = nRT (Pressure times volume equals the number of moles times the ideal gas constant times temperature)

12. Coulomb's Law: F = k(q₁q₂)/r² (Force between two charges equals Coulomb's constant times the product of the charges divided by the distance squared)

13. Gravitational Force: F = G(m₁m₂)/r² (Force between two masses equals the gravitational constant times the product of the masses divided by the distance squared)

14. Centripetal Force: F_c = mv²/r (Centripetal force equals mass times velocity squared divided by the radius of the circular path)

15. Hooke's Law: F = -kx (Force exerted by a spring equals the spring constant times the displacement)

16. Torque: τ = rFsinθ (Torque equals the lever arm times the force times the sine of the angle between them)

17. Momentum: p = mv (Momentum equals mass times velocity)

18. Impulse: J = Δp = FΔt (Impulse equals the change in momentum, which equals force times change in time)

19. Shear Modulus: (shear stress)/(shear strain) = (F/A)/(x/y)

20. Water Pressure: Pressure = ρgh (Pressure equals density times the acceleration due to gravity times height)

This list provides a foundational overview. More specialized areas, such as quantum mechanics or relativity, rely on their own sets of critical equations.