Exam 2 : Torques

Centric forces are those that act

through an objects center of mass

What forces will only result in linear changes in position?

Centric Forces

Eccentric Forces are those that are

not directed through a objects center of mass

What force will cause linear and angular(rotational) changes in position

Eccentric Forces

The turning effect of an eccentric force is called

torque

In order for rotation to occur, what type of force is required ?

Eccentric Force

What is torque?

Vector

The rotational effect of an eccentric force

Units: Nm

Moment arm is the

perpendicular distance between the axis and the line of force application

Torque is changed throughout the movement because what changes?

the moment arm

What is a lever

Whenever a movement occurs around an axis

• can be a set of rigid segments with an axis

• Many bones’ primary purpose is to act as one

What are the 3 main components for a lever system?

1. External force, load or resistance (weight of our bodies)

2. Internal Force, Effort or Muscle Force (how we move the load)

3. Fulcrum, Axis, or Pivot Point (often a joint)

What is a class 1 lever?

The internal and external forces are on opposite sides of the fulcrum

• ex) external resistance (weight of head) acting on one side of the fulcrum (alanto-occipital joint) and the internal force (all of the neck extension muscles) acting on the other side