Ch. 13 - Torque & Levers

What is torque?

The rotary effect of force

Formula of torque

T = Fd(perp)

What is a "moment arm"

Shortest perpendicular distance between a force's line of action and axis of rotation

T/F: If a force is directed through an axis of rotation, torque is produced

False

No torque because there there is no moment arm (d = 0)

For any given muscle, the moment arm is largest when the angle of muscle pull on the bone is closest to

a. 0 degrees
b. 45 degrees
c. 90 degrees
d. 180 degrees

c. 90 degrees

For a muscle to generate a constant joint torque during an exercise, it must produce more or less force as the moment arm decreases?

More force

Complete Sample Problem 7.1

Complete Sample Problem 7.1

Complete Sample Problem 7.2

Complete Sample Problem 7.2

Complete Sample Problem 9.1

Complete Sample Problem 9.1

Complete Sample Problem 13.1

Pg. 414

Levers

simple machine consisting of a relatively rigid, barlike body that may be made to rotate about an axis

Fulcrum

point of support, or axis, about which a lever may be made to rotate

First class lever

lever positioned with the applied force and the resistance on opposite sides of the axis of rotation

Second class lever

lever positioned with the resistance between the applied force and the fulcrum

Third class lever

lever positioned with the applied force between the fulcrum and the resistance

A wheelbarrow is an example of which lever class?

a. First
b. Second
c. Third

b. Second

The head is an example of which lever class?

a. First
b. Second
c. Third

a. First

A seesaw is an example of which lever class?

a. First
b. Second
c. Third

a. First

An upward bicep curl is an example of which lever class?

a. First
b. Second
c. Third

c. Third

A nutcracker is an example of which lever class?

a. First
b. Second
c. Third

b. Second

(force on end handles, resistant nut in middle, axis of rotation at other end of device)

Paddling an ore through water is an example of which lever class?

a. First
b. Second
c. Third

c. Third

Scissor motion is an example of which lever class?

a. First
b. Second
c. Third

a. First

A downward bicep curl is an example of which lever class?

a. First
b. Second
c. Third

b. Second

(muscle acts as a form of resistance as gravity/weight of dumbbell pulls arm down)

Which lever class is good for speed, as well as the most common in the body?

Third class