IB Sports, exercise and health science B.2 Forces, Motion and Movement Key Definitions

Acceleration is the rate of change of velocity over time.

Air resistance describes the forces that are in opposition to the relative motion of an object as it passes through the air.

Angle of projection is the angle formed by the initial velocity of a body and the horizontal plane through which the body is thrown.

Angular acceleration is the rate at which angular velocity changes over time.

Angular displacement refers to the change in the angular position of a rotating body.

Angular momentum measures the amount of rotational motion an object has or can achieve.

The motion of a body about a fixed point or fixed axis

Angular velocity measures the rate at which an object rotates around an axis.

When fluid velocity increases, pressure decreases, and vice versa. This principle explains how lift is generated in sports.

Buoyancy is the upward force exerted by a fluid (air or water) that opposes the weight of an object submerged in it.

A number that measures how much friction exists between two surfaces. It's also a measure of how much force is required to move an object across a surface

A collision occurs when two or more objects come into contact and exert forces on each other over a short period of time.

Conservation of angular momentum is a physical property of a spinning system such that its spin remains constant unless it is acted upon by an external torque

A continuous skill is a repetitive movement that has no clear beginning or end. It's a cycle of movements that are repeated over and over again. Examples of continuous skills include running, cycling, and swimming

Coordinates measure distance from an origin (e.g., in meters) and are given in two dimensions (x, y: horizontal and vertical) or three dimensions (x, y, z: horizontal, vertical, lateral). Two systems for three-dimensional coordinates: System 1: x = horizontal, y = vertical, z = lateral and System 2: x = horizontal, y = lateral, z = vertical. Angular coordinates are measured as angles around one or more axes.

The critical instant phase is the moment of contact or release of a movement, such as when a ball is struck in tennis or when a diver loses contact with the water. It's a crucial phase that determines the effectiveness of a skill.

A discrete skill is a single action with a clear beginning and end. It can be repeated, but the performer must start from the beginning.

Displacement is the shortest straight-line distance between an object’s starting and ending positions, including direction.

Distance is the total length of the path traveled by an object, regardless of direction.

Drag is the resistive force that opposes the motion of an object through a fluid.

Dynamic friction is the force that resists the motion of an object that is already moving. It's also known as kinetic friction.

The ability to do work, which is the ability to exert a force causing displacement of an object.

External factors such as temperature, humidity, air pressure, wind, water salinity, and altitude that affect the forces acting on objects and athletes during sport performance.

Follow-Through Phase refers to the final stage of a movement or action, where the body gradually decelerates and returns to a stable position after completing the primary action, essentially allowing for a smooth transition to the next movement or rest; it is the "finishing" part of the motion, like the controlled landing after a jump or the wrist flick at the end of a basketball shot.