Mechanics of human movement: Torque

What is angular displacement?

• change in absolute position experienced by a rotating line

Does the body achieve linear motion through rotation?

• yes

Most of the motions in the body are…

• rotations of segments about joints

• these angular motions coordinate to produce linear motion (walking, running, throwing) 

What is the moment of force? 

• the turning effect produced by a force 

• Torque 

What is the moment of force (torque) influenced by?

• Position and orientation of the force line of action

• magnitude of force

What is torque?

• Torque is the turning effect produced by a force and is equal to the product of the force magnitude and perpendicular distance between the line of action and axis of rotation

What are the units of torque?

• N*m

What is the moment arm? 

• Perpendicular distance between the line of action and the axis of rotation 

What are the steps to drawing a moment arm?

1. Identify the force’s line of action

2. Draw a line parallel to the force’s line of action

3. Draw a line perpendicular to 1 and 2

To describe a moment of force, what do you need?

• magnitude

• sense of the turning effect (clockwise vs. counterclockwise)

Would you rather use more force or increase the moment arm if you want to increase your strength capabilities?

• increase moment arm because human force is limited