Lesson 2: Levers

Question 1

What is a fulcrum?

Answer 1

• The point about which the lever rotates.

Question 2

What is resistance?

Answer 2

• The weight to be moved by the lever system.

Question 3

What is effort?

Answer 3

• The force applied by the user of the lever system.

Question 4

Levers

Answer 4

• The skeleton forms a system of levers that allows us to move.
• The bones act as levers, the joints are the fucrums, the effort is provided by the muscle and the resistance is the weight of the body part that is being moved.

Question 5

First class levers…

Answer 5

• Fulcrum is lcated between the effort and resistance
• Example: head and neck (flexion/extension) and the elbow (extension)

Question 6

Second class levers…

Answer 6

• Resistance is located between the fulcrum and the effort.
• Example: plantarflexion

Question 7

Third class levers…

Answer 7

• Effort is lies between between the fulcrum and resistance.
• Can be found in all other joints of the body
• Example: hip/knee/elbow flexion

Question 8

What is effort arm?

Answer 8

• The length of the line between where the fulcrum and effort are labelled

Question 9

What is resistance arm?

Answer 9

• The length of the line between where the fulcrum and resistance are labelled

Question 10

What is mechanical advantage?

Answer 10

• When the effort arm is longer than the resistance arm

Question 11

What is mechanical disadvantage?

Answer 11

• When the resistance arm is longer than the effort arm.

Question 12

Which lever has a mechanical advantage?

Answer 12

• Second class: plantarflexion of the ankle
• Adv: Can generate much larger forces. Lifts the whole body weight.
• Disadv: slow, with limtied range of movement

Question 13

Which lever has a mechanical disadvantage?

Answer 13

• First class: triceps in extension of the elbow
• Third class: biceps in flexion of the arm
• Adv: large range of movement and any resistance can be moved quickly.
• Disadv: cannot apply much force to move an object.