F = ma — Force equals mass times acceleration. Enter any two values to calculate the third. Enable friction to include real-world effects like sliding resistance.
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Understanding Force and Newton's Laws
Force is a push or pull that can change an object's motion. Sir Isaac Newton's three laws of motion describe how forces affect the movement of objects, forming the foundation of classical mechanics.
Newton's Three Laws of Motion
- First Law (Inertia): An object at rest stays at rest, and an object in motion stays in motion unless acted upon by an external force.
- Second Law (F = ma): The acceleration of an object is directly proportional to the net force and inversely proportional to its mass.
- Third Law (Action-Reaction): For every action, there is an equal and opposite reaction.
Types of Forces
- Applied Force: A force applied to an object by a person or another object
- Gravitational Force (Weight): W = mg — the force of gravity on an object
- Normal Force: The support force perpendicular to a surface
- Friction Force: f = μN — resistance force opposing motion
- Tension: Force transmitted through a rope, string, or cable
Free Body Diagrams
A free body diagram (FBD) shows all forces acting on an object as vectors. This visual representation helps analyze the net force and predict the object's motion. Forces are drawn as arrows pointing in the direction they act, with length proportional to magnitude.
Units of Force
- Newton (N): SI unit — 1 N = 1 kg·m/s²
- Kilonewton (kN): 1 kN = 1000 N
- Pound-force (lbf): Imperial unit — 1 lbf ≈ 4.448 N
- Dyne (dyn): CGS unit — 1 dyn = 10⁻⁵ N