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Mechanisms of Aerial Locomotion
Falling- decreasing altitudes under gravity, no specializations for producing drag or lift- quickest way of escape for many animals
Parachuting- vertical displacement under gravity, specializations for increasing drag, minimize terminal velocity to slow down
- Gliding- lift generated without flapping, propulsion by jumping and gravity
- “flying lemur”, “flying” squirell, “flying” snake, Alsomitra macrocarpa seed- low
- terminal velocity
Flying- lift generated by flapping, propulsion by flapping
- Advantages- lots of sacromeres in parallel, no bulge, eg. arthropod leg
- Disadvantages- short escrusion, some force wasted due to fiber orientation
- A force in the direction perpendicular to traveling
- Can be up or down
- Generating by creating a circulatory force
- An increase in flow (Ek) results in a decrease in pressure (Ep)
- Force perpendicular to flow-Bernoulli's Effect
- Extension of the law of conservation of energy.
- Potential E in fluids is pressure and kenetic E is movement.
- Can't maintain one if the other changes
- In sponges, water flows over the top creating movement in the body of the sponge.
- Spring loaded inverted pendulum model or pogo stick model
- Mechanical E= Potential E + Kenetic E
Walking and Running
- The basic components of efficent terrestrial locomotion.
- A vector has both magnitude and direction.
- Within a lever system a muscle can not have both a high mechanical advantage and a high velocity ration.
- A muscle with a high mechanical advantage can increase speed by increasing muscle length.
- A muscle with a high velocity ratio can increase force production by increasing cross sectional area.
- The lever arms complete their arm movements during the same amount of time. A long lever has a greater displacement and so moves faster than a shorter lever.
- The longer the in level with respect to the out level, the higher the mechanical advantage and the more power the muscle can use against its load.
- product of force and lenght.
- Can change even if L0 and L1 are constant
Mechanics of a simple skeletomuscular system
Spindle shaped muscle
- part parallel fibered part pinnate
- a common compromise
Parallel Fibered Muscle
- Advantages- shorten rapidly, large excrusion
- Disadvantages- bulges during contraction, relatively few sacromeres in parallel (low force)
Design of Column and cylinders
- Hollow cylindrical elements are strong and light
- ex. arthrod leg segments, light poles, plant stems, vertebrate long bones
- Abdomonial coelom is a fluid filled space that is pressurized to provide support during lifting to help expel feces. When the force is too high and/or the coelomic wall is too weak stuff comes out... inguinal hernia
Design Principles of Skeletal Structures
- Build structures with multiple layers to prevent propagation of cracks
- Use composite materials- one good in compression and one good in tension
- stress-strain relationships of biomaterials are often time dependent
The strain imposed on a material at failure
The stress impossed on a material at failure
Kinds of Mechanical Forces
- Lift production
- The roboseed with samara from maple tree - spins around and chops air creating lift.
- Form of natural selection to carry it away from the parent tree.
- High kenetic energy on top and less pressure on the bottom pushing it up.
- Happens in curve balls and sail boats
- Snapping shrimp claps. Gasses dissolve in water and it makes bubbles then the cavitation slams shut creating a very intense shock wave
- Ailanthus tree (tree of heaven)- seed in the middle falls off the tree ans starts t twirl generating lift by autorotation. The horizontal force moves it away from the shadow of the tree
- Nonrotating object that imposses rotation of air.
- The speed of air increases over the curvator
- As soon as wing tip passes,air circulates and begins circulating in a trail
- Way of generating a magnus effect without spinning
- Occurs in birds and airplanes
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