PHYT103 WEEK 2 NOTES TOPIC 1 – motion, force and load

Flashcards covering kinematics, force types (internal/external), torque, movement arm, center of mass, force composition, and torque problem solving from PHYT103 Week 2 notes.

What does kinematics of motion describe?

Description of motion from a spatial and temporal perspective; the path of motion may be linear or angular; linear motion paths involve all points on the body moving the same distance in the same amount of time, with focus on direction, path, and speed.

How do linear motion and angular motion differ?

Linear motion occurs along a straight or curved path with all points moving the same distance in the same amount of time; angular motion is around an axis and different regions of the same object do not move through the same distance in a given time.

What is force?

A push or pull acting on an object; forces cannot be seen but their effects can be observed.

What are internal forces and their types?

Forces produced from structures within the body: Active (generated by muscle contraction) and Passive (generated by tension in stretched tissue).

What are external forces?

Forces produced outside the body, such as gravity, external loads, and friction.

What three characteristics describe forces?

Magnitude, direction, and point of application.

What can forces do to a body in biomechanics?

Translate a body segment or produce rotation (torque).

What is torque?

The rotatory effect of a force, producing rotation about an axis.

When does torque occur in biomechanics?

Torque occurs when a force tends to rotate a segment about an axis, especially if the segment is fixed or anchored.

How is torque calculated?

Torque (T) = Force (F) × Movement Arm (MA).

What is the movement arm (MA)?

The perpendicular distance from the force’s line of action to the axis of rotation.

What is the centre of mass?

The point where the weight of a limb (or body) is considered to be applied, effectively where gravity acts.

What does composition of forces mean?

The process of combining or adding two or more vectors into a single resultant.

What is the four-step approach to solving a biomechanics torque problem?

1) Identify forces involved (external/internal); 2) Identify the torque each force produces (external torque vs internal torque); 3) Identify the biomechanical principle involved; 4) Link the principle back to the question.

How can you reduce the effort for a given torque on a lever?

Apply the weight/force further from the hinge (increase the moment arm) to reduce the required force.