Biomechanics: Movement Fundamentals - Key Vocabulary

Vocabulary flashcards covering fundamental biomechanics concepts from the Movement Mechanics lecture notes.

Biomechanics

Study of the laws governing balance and movement in living organisms, focusing on forces and their effects on the human body.

Classical mechanics

Study of bodies in motion or at rest using concepts of force, acceleration, equilibrium, and static conditions.

Force

A push or pull acting on a body that can cause acceleration, deformation, or a change in motion; defined by magnitude, direction, line of action, and sense.

External forces

Forces applied from outside a system, such as gravity, contact forces, and friction.

Internal forces

Forces generated within the body, including active muscle forces and passive structures like ligaments.

Normal force (Fn)

Perpendicular reaction force exerted by a surface to prevent penetration; acts perpendicular to the surface.

Gravitational force (Fg)

Attractive force between masses; on Earth, Fg = m × g.

Frictional force

Force that opposes relative motion between two contacting surfaces; acts parallel to the surfaces and is related to the normal and gravitational forces.

Lever arm

Perpendicular distance from the pivot to the line of action of a force; also called the moment arm.

Moment (torque)

Rotational effect produced by a force about a pivot; M = F × d; measured in Newton-meters (N·m).

Center of Gravity (CG)

Point at which the body's weight can be considered to act; the average location of mass.

Work

Transfer of energy that causes displacement; W = F × d when force and displacement are in the same direction.

Energy

Capacity to perform work; can be stored or transferred; includes kinetic energy, gravitational potential energy, and elastic potential energy.

Kinetic energy (Ek)

Energy due to motion; Ek = 0.5 × m × v^2.

Gravitational potential energy (Ep_g)

Energy stored due to height in a gravitational field; Ep_g = m × g × h.

Elastic potential energy (Ep_e)

Energy stored due to deformation of an elastic object (e.g., spring); Ep_e = 0.5 × k × Δx^2.

Power

Rate of performing work or transferring energy; P = W/Δt or P = F × d / Δt.

Law of Cosines

Relates sides and angle in any triangle: a^2 = b^2 + c^2 − 2bc cos A (and permutations).

Pythagorean theorem

In a right triangle, a^2 + b^2 = c^2.

Sine

Ratio sin θ = opposite / hypotenuse in a right triangle.

Cosine

Ratio cos θ = adjacent / hypotenuse in a right triangle.

Tangent

Ratio tan θ = opposite / adjacent in a right triangle.

Inclined plane

A plane tilted at an angle θ; gravity components along the plane and a normal force Fn = m g cos θ.

Angle of inclination

Angle between the plane and the horizontal; used to resolve forces and compute components.

Effective force

Component of a force along the direction of motion; Fe = F cos α.

Force components

Decomposing a force into perpendicular components along chosen axes (e.g., horizontal and vertical).

Center of rotation

Pivot point about which rotation occurs; determines lever arms.

Work-energy principle

Work done on a system equals the change in its energy; W = ΔE; energy transforms or transfers.

Vector

An object with magnitude, direction, and sense; represented by an arrow; has a starting point and an ending point.

Scalar

A quantity described by magnitude only, with no directional component.