Types of Machines in the body

Question 1

What is the definition of torque? What is the formula?

Answer 1

A rotatory force when the line of action of a force does not pass through the axis of rotation

Torque = Force x Moment Arm
T = F x r
T units = Nm

Question 2

What is the moment arm and how is it measured

Answer 2

The moment arm is the perpendicular distance btw the line of action of the force and a parallel line passing though the object’s axis of rotation

Question 3

What are the three components of a lever system

Answer 3

Fulcrum - joint -axis of rotation (A)

Force/Effort (F) of the muscle the counteract the resistance (R) forces (weight/external pushes)

Question 4

What are the three different types of lever systems?

Answer 4

First Class - Fulcrum in the middle of the F and R. Can have a high or low mech. advantage depending on the length of the FA and RA

Second Class - The FA and RA are on the same side opposite to the fulcrum/axis of rotation but the FA is greater than the RA, giving a larger mech. advantage

Third Class - The FA and RA are on the same side opposite to the fulcrum/axis of rotation but the RA is greater than the FA, creating a small mech. advantage

Question 5

What is static equilibrium?

Answer 5

When both external forces and external torques about the axis, sum to zero. This is an isometric contraction

Question 6

What are the three forces acting on a joint/lever system

Answer 6

F resistence
F effort
F joint reaction force (Equal and opposite to the force of the muscle pulling on the joint minus the counteracting force)

Question 7

What happens when the angle of a joint is chnaged?

Answer 7

The length of the moment arm also changes. Decreasing the length of the means the muscle is required to generate more force for the same length