Biomechanics and Newton's Laws of Motion

Unit 3 AOS 1: Improving Movement Skills

Biomechanical Principles for Analysis of Human Movement

• Newton's Laws of Motion: Key frameworks to analyze movement.

  • 1st Law (Inertia): An object remains at rest or in uniform motion unless acted upon by a force.

  • Example: A netball remains in hand until force is applied.

  • Inertia: Large mass leads to greater resistance to motion change.

  • 2nd Law (Acceleration): The acceleration of an object is proportional to the force applied and inversely proportional to its mass.

  • Formula: F = MA

  • Example: A small force causes slow acceleration; a large force increases acceleration.

  • If two objects of different mass are subjected to the same force, the lighter object accelerates faster.

  • Practical Application: Judging force needed for optimal movement, e.g., netball shooting.

  • 3rd Law (Action-Reaction): For every action, there is an equal and opposite reaction.

  • Forces exist in pairs; when two objects interact, they exert equal and opposite forces on each other.

  • Example: Bumper cars; when one car hits another, both react.

• Projectile Motion: Factors affecting projectile motion include height, angle, and speed of release.

• Anatomical Levers: Understanding of third-class levers, including axis, force, resistance, and mechanical advantage in motion.

• Equilibrium and Stability: Factors affecting stability include center of gravity, base of support, and line of gravity.

Newton's 1st Law of Motion

• Concept: Describes inertia.

  • An object at rest stays at rest; unless acted upon.

  • A cue ball at rest will not move until struck.

• Inertia Characteristics:

  • Greater mass requires more force to move/change motion.

Newton's 2nd Law of Motion

• Concept: Relation between force, mass, and acceleration.

• Application: 50N force on different masses illustrates accelerated motion.

• Key Takeaway: The lighter object accelerates faster under the same force.

Newton's 3rd Law of Motion

• Concept: Action and reaction forces.

• Examples: Basketball passing; each force causes an equal and opposite reaction.

• Ground Reaction Forces (GRF): Essential for movement. When walking/jumping, ground exerts upward and forward forces leading to motion.

• Athletic Applications: Crouch vs. standing starts affect performance due to variations in applied force and reaction forces.

• Momentum Transfer: When objects collide, momentum is conserved. E.g., in baseball, a bat transfers momentum to the ball upon impact.