Biomechanics: Chapter 2 Linear Kinematics

General Motion

A change in position that results from a combination of both linear and angular motion. Most movement is general in nature. Ex: In running the arms and legs move in angular motion while the trunk or center of mass or COG is linear motion.

Angular motion

Change in position that occurs when all point on a body or object move in circular paths about the same fixed axis, also referred to as a rotary motion or rotation. Ex: ice skater spinning in place.

Displacement (resultant displacement)

Is the distance traveled in a straight line from the starting point to the ending point.

Rectilinear translation

Linear motion that occurs when a object maintains its orientation during a movement so that all points on the object move the same distance, in the same direction, in the same time, in straight lines. Example: figure skating gliding across the ice in a static position, a bicyclist gliding on a flat surface.

Curvilinear translation

Linear motion that occurs when an object maintains its orientation during a movement so that all points on the object move the same distance, in the same direction, in the same time but not in straight lines.

Speed

Rate of motion of an object

Positive acceleration

Speeding up in a positive direction, the runner that has the best positive acceleration at the beginning of a sprint will lead and it they have the lease deceleration (negative acceleration) they will win.

Acceleration

When an object speeds up, slows down, starts, stop or changes direction, it is accelerating. Acceleration can be positive or negative.

Distance traveled

a measure of the length of a path followed by an object. (may be a straight path or curved)

Linear motion

is referred to as translation. It occurs when all points on a body or object move the same distance, in the same direction and at the same time. Linear motion happens in two ways rectilinear translation and curvilinear translation.

Negative acceleration

occurs when an object moves in a positive direction but is slowing down (some call this deceleration) Sprinters at the end of the race, typically it is the one who decelerates or has less negative acceleration who wins.

Kinematics

the branch of dynamics concerned with the description of motion. (motion is classified as linear, angular and general (a combination of both))