Biomechanics and Motion Principles

Vocabulary flashcards covering core biomechanics topics including linear and angular kinematics, kinetics, Newton's laws of motion, momentum, torque, and equilibrium principles.

Linear motion

Movement where all body parts move at the same speed in the same direction along a straight or curved line.

Angular motion

Movement occurring around a central axis.

General motion

A combination of linear and angular motion.

Linear displacement

The shortest distance between the starting and finishing point, measuring how far a body has moved.

Speed

The rate of change of distance, defined mathematically as $\text{Speed} = \frac{\text{distance}}{\text{time}}$.

Velocity

The speed of a body in a specific direction and the rate of change of displacement, calculated as $\text{Velocity} = \frac{\text{displacement}}{\text{time}}$.

Acceleration

The change in velocity given in a period of time, calculated as $\text{Acceleration} = \frac{\text{change in velocity}}{\text{change in time}}$.

Positive acceleration

A state where velocity is increasing.

Negative acceleration

A state where velocity is decreasing.

Zero acceleration

A state where velocity is constant.

Force

A push or a pull that can affect an object's shape and move an object.

Friction

A force that always acts in the opposite direction to the motion of an object, resisting movement when the object and surface are in contact.

Drag force

Air and water resistance that opposes the direction of motion of a body as it moves through air or water.

Gravitational force

Forces of attraction that exist between any two objects with mass.

Mass

The amount of matter in an object telling how many particles it has; measured in kilograms and independent of where it is measured.

Newton's first law

The principle stating that an object will remain at rest or in constant motion unless acted upon by an external force.

Newton's second law of motion

The principle stating that a force applied to an object will produce a change in motion in the direction of the force that is directly proportional to the force ($\text{Force} = \text{mass} \times \text{acceleration}$).

Newton's third law of motion

The principle stating that for every action, there is an equal and opposite reaction.

Inertia

The tendency of the body to resist change in a state of motion with a constant velocity.

Momentum

The measure of the amount of motion an object has and its resistance to changing that motion, calculated as $\text{Momentum} = \text{mass} \times \text{velocity}$.

Follow through

A technique that allows for maximum time force is applied past the greater momentum of an object.

Impulse

The measure of the change in momentum of a body, calculated as $\text{Impulse} = \text{force} \times \text{time}$.

Angular distance

The total amount of angular distance covered during motion.

Angular displacement

The difference between the initial and final angular position.

Angular speed

The rate calculated as angular distance divided by time ($\frac{\text{distance}}{\text{time}}$).

Angular velocity

The rate calculated as angular displacement divided by time.

Angular acceleration

The rate of change calculated as the change in angular velocity divided by time.

Torque

An eccentric force that does not act through an object's center of gravity, calculated as $\text{Torque} = \text{force} \times \text{lever arm}$.

Momentum of inertia

A body's tendency to resist change in rotary position, defined mathematically as $\text{mass} \times \text{radius}^2$.

Angular momentum

The quantity calculated as $\text{Moment of inertia} \times \text{angular velocity}$, which remains constant unless acted upon by an external torque.

Conservation of angular momentum

The principle that angular momentum remains conserved when a body is in flight.

Static equilibrium

The state of motion at rest during movement where all forces and torques are balanced.

Dynamic equilibrium

The state of motion and velocity during movement where all forces and torques are balanced.

Balance

The ability to control equilibrium while stationary or moving.

Stability

A body's ability to resist change in its current state.

Base of support

The area beneath a person or object.

Center of gravity

The average location of the weight of an object as the single balance point where its mass is evenly distributed in all directions.

Line of gravity

An imaginary vertical line that extends straight from the center of gravity of an object to the ground.