SI unit of force.

## The reasoning Force is what causes objects to accelerate — think of pushing a book or kicking a ball. In Physics, we define force using **Newton's Second Law**: F = ma (force equals mass times acceleration). The SI unit must match this definition: - Mass is measured in kilograms (kg) - Acceleration is measured in metres per second squared (m/s²) - So force = kg × m/s² = **Newton (N)** One Newton is the force needed to accelerate 1 kg of mass at 1 m/s². Simple! ## Why the wrong options tempt you **A) Joule** — This measures *energy* or *work* (force × distance). Easy to confuse because both involve force, but Joule measures the *result* of applying force over a distance. **C) Watt** — This measures *power* (energy per time). Students mix this up because force, energy, and power are related, but they're different quantities. **D) Pascal** — This measures *pressure* (force per area). Pressure uses force in its formula, but it's force *spread over* an area, not force itself. ## Quick takeaway **Force makes things move → Newton. Energy from movement → Joule. Pressure from spreading force → Pascal.** Each quantity has its own unit!