Newton's Second Law of Motion:

* F = ma

* F: Force (in Newtons, N)

* m: Mass (in kilograms, kg)

* a: Acceleration (in meters per second squared, m/s²)

Force Due to Gravity:

* F = G(m₁m₂)/r²

* F: Force of gravity (in Newtons, N)

* G: Gravitational constant (6.674 × 10⁻¹¹ N⋅m²/kg²)

* m₁: Mass of object 1 (in kilograms, kg)

* m₂: Mass of object 2 (in kilograms, kg)

* r: Distance between the centers of the two objects (in meters, m)

Weight:

* W = mg

* W: Weight (in Newtons, N)

* m: Mass (in kilograms, kg)

* g: Acceleration due to gravity (approximately 9.8 m/s² on Earth)

Friction:

* f = μN

* f: Frictional force (in Newtons, N)

* μ: Coefficient of friction (a dimensionless value)

* N: Normal force (in Newtons, N)

Spring Force:

* F = -kx

* F: Spring force (in Newtons, N)

* k: Spring constant (in Newtons per meter, N/m)

* x: Displacement from equilibrium (in meters, m)

Electrostatic Force:

* F = k(q₁q₂)/r²

* F: Electrostatic force (in Newtons, N)

* k: Coulomb's constant (8.98755 × 10⁹ N⋅m²/C²)

* q₁: Charge of object 1 (in Coulombs, C)

* q₂: Charge of object 2 (in Coulombs, C)

* r: Distance between the centers of the two objects (in meters, m)

Magnetic Force on a Moving Charge:

* F = qvBsinθ

* F: Magnetic force (in Newtons, N)

* q: Charge of the particle (in Coulombs, C)

* v: Velocity of the particle (in meters per second, m/s)

* B: Magnetic field strength (in Tesla, T)

* θ: Angle between the velocity vector and the magnetic field vector

Note: These are just a few of the many force formulas in physics. The specific formula you need will depend on the situation you are analyzing.