A force of 20 N acts on a mass of 4 kg. The acceleration is:

**The reasoning** This is pure **Newton's Second Law of Motion**: F = ma (Force = mass × acceleration). You have: - Force (F) = 20 N - Mass (m) = 4 kg - Acceleration (a) = ? Rearrange the formula: a = F/m So: a = 20/4 = **5 m/s²** That's it! When a force pushes an object, the acceleration depends on how heavy it is. Bigger mass = harder to accelerate. **Why the wrong options tempt you** - **A (0.2)**: You divided wrong — 4/20 instead of 20/4. Always put force on top! - **C (16)**: You subtracted (20 − 4). Newton's law uses division, not subtraction. - **D (80)**: You multiplied (20 × 4). That gives you the force if you already knew acceleration — backwards thinking! **Quick takeaway** To find acceleration, always divide force by mass: **a = F/m**. The heavier the object, the slower it accelerates under the same force — just like pushing a bicycle versus pushing a car!