levers

Question 1

• what is the fulcrum

Answer 1

point about which the lever rotates

Question 2

what is the resistance

Answer 2

the weight to be moved by the lever system

Question 3

what is the effort

Answer 3

the force applied by the user (muscle) of the lever system

Question 4

first class levers

Answer 4

• fulcrum in the middle
• effort down
• movement of head and neck during flexion and extension
• extension of the elbow

Question 5

2nd class levers

Answer 5

• resistance in the middle
• effort up
• plantarflexion of the ankle

Question 6

3rd class levers

Answer 6

• effort in the middle
• effort up
• found in all other joints of the body
• hip, knee, elbow flexion

Question 7

what is mechanical advantage

Answer 7

where the effort arm is longer than the resistance arm
- can move large load over a shprt distance and requires little force

Question 8

what is mechanical disadvantage

Answer 8

where the resistance arm is longer than the force arm
- cannot move as heavy load but can do it faster
- also has large range of movement

Question 9

what is the effort arm

Answer 9

length of the line between the fulcrum and effort

Question 10

what is the resistance arm

Answer 10

length of the line between the fulcrum and the resistance

Question 11

second class plantar flexion of ankle

Answer 11

mechanical advantage:
- can generate much larger forces
- has to lift the whole body weight
mechanical disadvantage:
- slow with a limited range of movement

Question 12

first class triceps in extension of elbow
third class biceps in flexion of the arm

Answer 12

mechanical advantage:
- large range of movement and any resistance can be moved quickly
mechanical disadvantage:
- cannot apply much force to move an object