Sport Science Levers, laws of motion

Lever

A fundamental simple machine that consists of a rigid rod or beam that pivots around a fixed point called the fulcrum. When a force is applied at one end of the lever, it causes an increased force or motion at the other end.

Mechanical advantage

A measure of the efficiency of a lever, calculated as the ratio of the load force (output) to the effort force (input). A higher mechanical advantage indicates an easier lift or movement of the load.

First-class lever

A lever system in which the fulcrum is located between the effort force and the load force. Depending on the relative distances to the fulcrum, the lever can amplify the effort or increase the load's speed.

Second-class lever

A lever in which the load is positioned between the effort and the fulcrum. In this configuration, a smaller effort can lift a larger load, as the effort arm is longer than the load arm, exemplified by a wheelbarrow.

Third-class lever

A lever where the effort force is applied between the load and the fulcrum. This type of lever requires a larger effort to move a smaller load, accentuating the speed and distance the load can be moved, such as in a fishing rod.

Friction

A opposing force that arises when two surfaces come into contact, resisting the sliding motion between them. Friction is crucial for movement control, providing the necessary grip but also wasting energy in the process.

Static friction

The force that must be overcome to start moving an object at rest. It is typically greater than dynamic friction, as it prevents an object from beginning to slide.

Dynamic friction

The frictional force encountered between two surfaces sliding past each other. It is generally less than static friction and is crucial in describing motion resistance once an object is in motion.

Kinematics

The branch of mechanics that deals with the description of motion without regard to the forces that cause it. Kinematics encompasses various types of motion, such as linear, curvilinear, angular, and general motion.

Vector measurement

A type of measurement characterized by both size (magnitude) and direction. Examples include velocity, which indicates how fast something is moving and in which direction, and force, which has both an amount and a direction of application.

Scalar measurement

A type of measurement that includes only magnitude without any directional component. Common examples are speed (the rate of motion), volume (the amount of space occupied), and weight (the force exerted by gravity on an object).

Linear velocity

A vector quantity that describes the speed of an object in a straight line, along with the direction of that motion. It is calculated by dividing the change in position (displacement) by the change in time.

Linear momentum

A vector quantity associated with the motion of an object, calculated as the product of its mass and its velocity. It is a conserved quantity in isolated systems, meaning the total momentum remains constant if no external forces act on it.

Impulse

The change in momentum experienced by an object when a force is applied over a time interval. Mathematically defined as the product of the average force applied and the duration of time the force acts.

Torque

A measure of the rotational force applied to an object. It is the tendency of a force to cause rotation about an axis and is calculated as the product of the force applied and the distance from the point of rotation (lever arm).

Moment of inertia

A physical quantity that indicates how difficult it is to change the rotational motion of an object around an axis. It depends on the object's mass distribution relative to the axis of rotation.

Conservation of angular momentum

A fundamental principle stating that in an isolated system with no external torques, the total angular momentum remains constant. This means the motion of rotating bodies will remain undisturbed unless acted upon by an external force.

Anthropometry

The scientific study of human body measurements and proportions, used extensively to optimize ergonomic design, ensuring that tools and environments fit the users and promote comfort and efficiency.

Ergonomic design

The process of designing equipment or environments to minimize discomfort and enhance productivity by fitting the task to the user’s physical and cognitive abilities, leading to reduced fatigue and improved performance.

Circumduction

A complex joint movement that involves a conical motion, wherein a body segment moves in a circular fashion, typically observed at ball-and-socket joints like the shoulder or hip.

Pronation

A rotational movement where the palm faces downward or the sole of the foot turns inward. It is a natural action, particularly when walking or running, but excessive pronation can lead to biomechanical issues.

Supination

The opposite of pronation, this movement involves the rotation where the palm faces upward or the sole of the foot turns outward. It plays an essential role in the biomechanics of the arms and legs during motion.