5.2 Levers (not complete - include examples)

Question 1

Identify what components a lever consists of

Answer 1

1. Fulcrum
2. Resistance
3. Effort

Question 2

Bones act as ___. The joints are the ___, the ___ is provided by the ___ and the ___ is the weight of the body part/object being moved against the force of ___.

Answer 2

Bones act as lever. The joints are the fulcrums, the effort is provided by the muscles and the resistance is the weight of the body part/object being moved against the force of gravity.

Question 3

Identify the classifications of levers

Answer 3

First class lever
Second class lever
Third class lever

Question 4

Identify and describe the classifications of levers

Answer 4

First class lever - EFR
Second class lever - FRE
Third class lever - FER

Question 5

Explain what is meant by a mechanical advantage and disadvantage

Answer 5

Mechanical advantage: the force arm is longer than the resistance arm, meaning the lever system can move a large load/resistance over a a short distance and needs little force/effort. It has a small range of movement. The lever can overcome a large load/resistance with relatively little effort.

Mechanical disadvantage: the resistance arm is greater than the force arm. This lever system cannot move as heavy a load/resistance but can do it faster. It has a large range of movement.

be moved is said to provide a mechanical disadvantage.

Question 6

Give an example of a first class lever in the body

Answer 6

• Neck extension
• Tricep Extension

Question 7

Give and example of a second class lever in the body

Answer 7

• Ankle during plantar flexion

Question 8

Give an example of a third class lever in the body

Answer 8

Third class levers can be found anywhere else in the body:

• Hip
• Knee
• Elbow flexion

Question 9

Explain what mechanical advantage/disadvantage depends on

Answer 9

Mechanical advantage/disadvantage depends on the length of the effort arm and the resistance arm. The effort arm is the distance between the fulcrum and the ‘effort’. The resistance arm is the distance between the fulcrum and the resistance.

Question 10

Explain the characteristics of mechanical advantage and disadvantage

Answer 10

Mechanical advantage: when the effort arm is longer than the resistance arm. The lever can move a large load over a short distance with little effort. Small range of movement

Mechanical disadvantage: when the resistance arm is longer than the effort arm. The lever cannot move as heavy load as mech. adv. but can do it faster. Large range of movement.