Kinetic Concepts for Analyzing Human Motion

Flashcards covering key concepts in Kinetic Concepts for Analyzing Human Motion.

Kinematics

Description of motion as a function of space and time without considering the forces causing the motion.

Kinetics

Relationship between the forces acting on a system and the motion of that system.

Mass

Quantity of matter composing an object; measure of inertia for linear motion.

Center of Mass

Point representing the average location of the mass of a body.

Weight

Force due to gravity acting on an object; equal to mass times acceleration due to gravity.

Inertia

Tendency of an object to resist changes in its state of motion.

Newton's 1st Law

A body will maintain a state of rest or constant velocity unless acted upon by an external force.

Newton's 2nd Law

Net force acting on a body is equal to mass multiplied by acceleration (Σ F = ma).

Newton's 3rd Law

For every action, there is an equal and opposite reaction.

Momentum

Quantity of motion possessed by a body, calculated as the product of mass and velocity (M = mv).

Impulse

A measure related to the net effect of applying a force for a time (J = Ft).

Coefficient of Restitution

Measures the elasticity of a head-on impact; value ranges from 0 (perfectly plastic) to 1 (perfectly elastic).

Mechanical Work

Product of a force applied against a resistance and the displacement of that resistance in the direction of the force.

Kinetic Energy (KE)

Energy of motion, calculated as KE = ½mv².

Potential Energy (PE)

Energy by virtue of a body’s position or configuration, calculated as PE = mgh.

Static Friction

Force that opposes the initiation of motion between two surfaces that are in contact and at rest.

Kinetic Friction

Force that opposes the movement of two surfaces that are sliding against each other.

Free Body Diagram

A diagram showing all external forces acting on a system.

Net Force

Resultant force derived from the vector addition of two or more forces.

Linear Motion

All parts of an object move the same distance in the same direction at the same time.

Mechanical Energy

The capacity to do work, consisting of kinetic and potential energy.

Work-Energy Principle

States that the work done on an object equals the change in its kinetic energy.

Law of Conservation of Mechanical Energy

States that a body's mechanical energy remains constant when only gravity acts on it.

Friction

Force acting over the area of contact between two surfaces, opposing motion.

Elastic Collision

Collision where no kinetic energy is lost; objects bounce off each other.

Plastic Collision

Collision where objects deform and stick together.

Normal Reaction Force (R)

Force exerted perpendicularly by a surface on an object in contact with it.

Force Applied (F)

The push or pull on an object, which can change its state of motion.

Resultant Force

The overall force acting on an object when all the individual forces acting on it are combined.

Magnitude of Force

The size or strength of a force, often measured in Newtons (N).

Acceleration

The rate at which the velocity of an object changes with time.

Direction

The line along which something moves or points.

Displacement (d)

The shortest distance from the initial to the final position of an object.

Torque

A measure of the force that can cause an object to rotate about an axis.

Energy Absorption

The process by which an object takes in energy during an impact.

Application of Force

The act of exerting a force on an object to cause it to move or change direction.

Vector Quantity

A quantity that has both magnitude and direction.

Scalar Quantity

A quantity that has only magnitude and no direction.

System of Objects

A collection of objects that are analyzed together in mechanics.

Angle of Impact

The angle at which two objects collide with one another.

Height of Drop (h)

The vertical distance from which an object is dropped.

Velocity Before Impact (v)

Speed and direction of an object just prior to colliding with another object.