Levers,muscles and skeletons

Question 1

What is a lever

Answer 1

rigid object that can pivot around an axis

can amplify force or distance

Question 2

What are the components of a lever

Answer 2

fulcrum, effort, load

Question 3

What are the 3 different classes of lever

Answer 3

1st class: fulcrum in the middle
2nd class: load in the middle
3rd class: effort in the middle

Question 4

What is a mechanical advantage

Answer 4

(amplification or reduction ) in force due to relative lengths of the effort or load arm
MA= F_L / F_E =d_e / d_l

Question 5

What is a distance advantage

Answer 5

amplification or reduction in distance moved due to the relative lengths of the effort or load arm
DA = F_E/ F_L = d_l / d_e

Question 6

Describe how the arms of a mole would work in terms of mechanical or speed advantage.

Answer 6

Moles need to have a mechanical advantage this means that the distance to the effort is relatively greater than other animals compared to the distance to the load. this is so they can push soil out of the way easily

Question 7

Why do muscles attach so close to the fulcrum

Answer 7

This is to reduce the distance from the effort to the fulcrum such that we would have a greater distance advantage, allows long movement of the limbs ***because muscles are good at producing forces but are not good in stretching

Question 8

What affects the force a muscle can produce

Answer 8

the cross sectional area of the muscle

Question 9

What does the muscle volume affect

Answer 9

work done by the muscle ( since force* distance = work; cross sectional area * muscle shortening length = work)

Question 10

What are the differences between pennate and parallel muscles

Answer 10

pennate:
- at oblique angle
- shorter muscle fibers- short contraction
- more force
- more fibers per muscle volume
- do not bulge
parallel:
- long muscle fibers- long contraction
- muscle fibers are aligned along muscle contraction
- less muscle fibers per muscle volume
- bulge
- less force

Question 11

What is gearing in muscles

Answer 11

trading force for distance. skeletal system alters how a force generated by a muscle translates into high force/ short distance or low force/long distance

Question 12

What are the 2 factors that can be affected by muscle arrangement

Answer 12

1. velocity of contraction

2. force generated by muscles

Question 13

What is the AGR

Answer 13

architectural gear ratio= velocity of muscle contraction/ velocity of fiber contraction

Question 14

What is the AGR of parallel muscles

Answer 14

1

Question 15

What affects the rate of contraction in pennate muscles

Answer 15

the oblique angle of the muscle fiber arrangement

Question 16

When the pennation angle is greater is the contraction speed faster or slower

Answer 16

muscle contraction is faster at greater angles

Question 17

What is the tradeoff for changing the pennation angle

Answer 17

the greater the angle the faster the muscle contraction but the less force is generated in the direction of the muscle. the smaller the angle the slower the muscle contraction but the greater force is generated in the direction of the muscle

Question 18

Describe how the grasshopper jumps

Answer 18

1. semi-lunar process: stores a great deal of energy
2. extensor and flexor contract slowly, bends the semi lunar process and stores energy in the elastic cuticle
3. flexor releases suddenly and the cuticle releases stored energy rapidly