biomechanics

• Biomechanics is the science that studies living things from a mechanical perspective
• Linear motion occurs in a straight line or a curved path
• Angular motion takes place when a body moves along a circular path (rotation)
• Factors influencing motion include mass, velocity, force, and inertia
• The heavier an object, the greater its inertia
• Force is when an object acts on another object (push/pull) and is measured in Newtons
• Direct contact force examples: racquet on the ball
• Gravity is the force of attraction between two objects, pulling us down on Earth
• Friction occurs when two surfaces contact each other, opposes motion, and can be increased or decreased to improve performance
• Drag force is a frictional force that increases as speed increases, important in swimming for reducing drag
• Newton's First Law (Law of Inertia): an object remains at rest or in constant motion unless acted upon by an external force
• Newton's Second Law (Law of Acceleration): force = mass x acceleration
• Lighter objects accelerate faster with the same force applied
• Newton's Third Law (Law of Action Reaction): for every action, there is an equal and opposite reaction
• Momentum is mass x velocity, representing the amount of motion and resistance to changing that motion
• Greater mass leads to greater momentum at the same velocity
• Conservation of Momentum: when two objects collide, the change in momentum will be in the direction of the object with the greatest initial momentum
• Impulse is force x time, causing a change in momentum of an object
• Greater impulse leads to a greater change in momentum
• Summation of Momentum: correct timing and sequencing of body segments and muscles for maximal velocity
• Angular motion is movement around an axis (internal or external)
• First Law of Angular Motion: angular momentum remains constant unless acted upon by an external torque
• Second Law of Angular Motion: torque causes a change in angular motion proportional to its size and inversely proportional to the moment of inertia
• Moment of Inertia: tendency to resist changes in rotation
• Third Law of Angular Motion: for every torque, there is an equal and opposite torque
• Angular momentum is the product of moment of inertia and angular velocity, conserved in flight unless altered
• Location of mass affects an object's moment of inertia
• Conservation of Angular Momentum: angular momentum is constant while airborne unless position is altered
• linear motion is movement along a straight line or curved path
• distance is how how far an object has travelled total
• displacement is the change in position from start to finish
• speed = distance/time
• velocity = displacement/time
• acceleration

  change in velocity over a period of time
• when acceleration is at zero, it's either at rest or travelling at a constant velocity (you can have negative acceleration)
• angular distance is the sum of all angular changes
• angular displacement is the difference between initial and final position