Biomechanics - The Load on a Muscle

Question 1

Kinetics vs Kinematics

Answer 1

Kinetics - how much force is being produced at the muscles

Kinematics - what position are the joints, what velocities are they moving

Question 2

Moment arm

Answer 2

the shortest perpendicular distance between a force’s line of action and the axis of rotation

Question 3

Joint moment

Answer 3

The turning effect of a force applied to a rotational system at a distance form the axis of rotation; also known as torque

Force x Moment arm = Torque

Question 4

What is the difference between Mass and weight

Answer 4

Mass

• the amount of “matter” in an object (kg)

Weight

• the force exterted on an object by gravity (N, neutons)

*A 1kg oject will have a different weight on the earth vs the moon*

Question 5

What happens when you change the moment arm

Answer 5

decreasing the moment arm increases the amount of force needed to maintain/ initiate movement

Question 6

Net Joint Force

Answer 6

A net joint force is the minimum force required at a joint to obtain the observed kinematics; no motion