PhysicsBeginner8 min read • October 4, 2025

F = ma: Newton's Second Law

Double the force, double the acceleration—if mass stays the same.

The Formula

F = m × a

Force (newtons) = Mass (kg) × Acceleration (m/s²)

Example

A 10 kg cart accelerates at 2 m/s². Required force: F = 10 × 2 = 20 N.

Common Mistakes

  • Forgetting friction or opposing forces
  • Confusing mass and weight
  • Using inconsistent units

Practice Idea

Time how long a toy car takes to reach a certain speed with different added masses. Notice the change.

Next: Ideal Gas Law →