Pre-midterm Prep Flashcards
What are Newton’s Three laws?
- A body stays at rest or in uniform motion in a straight line unless a force is applied.
- Acceleration is proportional to the applied force and is in the same direction as the force.
- When one body exerts a force on another, the second always exerts a force on the first; the two forces are equal in magnitude, opposite in direction, and act along the same line.
What is Biomechanics?
The application of physics and engineering principles to biological problems.
Define design. Biological terms.
process by which a functional structure is created.
Biology = evolution. Random changes can lead to competitive advantages.
Biologist starts with a design (or structure) and then figures out the function of it, where the trade offs are etc.
What are the basic forces on structures in water?
buoyancy Thrust Drag Mg Lift -generated by hydrofoils Added Mass - acceleration of fluid around structure increases body mass.
What are the basic forces on structures in air?
Lift
Mg
Thrust
Drag
What are the basic forces on structures on the ground?
Ma
deal with forces much larger than body weight cause acceleration and deceleration are greater than that of gravity.
What are the basic forces of terrestrial locomation?
- Animal pushes off land and moves through the air.
- Earth offers lots of resistance, air not so much
- focus on ground reaction force (force needed to drive self forward) not air resistance.
What happens to the mechanical work generated by muscles? (terrestrial)
It generates the ground reaction force. the load elastic components or tendons help pay for the launch phase.
What are the forces involved in moving through a fluid?
-body pushes off and moved through same stuff. One part of body pushes on fluid, generating thrust, another part pushes fluid out of the way, generating drag
What happens when you increase the density and viscosity of a fluid?
you increase it’s resistance to movement
How do you push against the fluid to produce thrust but not push against the fluid to create drag?
Streamlining
What happens to the mechanical work generated by muscles? (fluid)
Creates vlorticies, pushes against air to generate thrust.
Efficiency = ?
Total work / metabolic cost
How do you visualize flow of fluid? to measure total work in swimming/flying?
- Introduce tracer in fluid (bubbles, dye,ec)
- Digital particle imaging velocimetry (DPIV)
- Computational fluid dynamics (not in course)
Cost = ?
Total metabolism + Waste + Gain
How can you reduce the maintenance cost (total metabolism and waste)?
Reduce activity cost of an animal.
Metabolic Rate =
Fuel + Oxygen = Bond energy available in fluid + reaction products (waste)
What is scaling?
The study of physical parameters as a function of body mass.
- power as a function of body mass
Equation for Energy
force x distance
Equation for Power
Energy / unit time
Minimum power = ?
resting metabolism
Resting metabolism = ?
Power expenditure at rest, in neutrally temperate conditions, in the post-absorptive state (not digesting)
Maximum power output = ?
some multiple of resting metabolism
Available power to do mechanical work = ?
Metabolic scope (maximum output - minimum output)
For a >100kg animal falling from what height will cause the animal injury?
the height of the animal itself
For a 100g - 100kg animal falling from what height will cause injury/
greater than the anima;s own height
100mg - 100g animal falling from what height will cause injury?
no height is too high
<100mg animal falling from what height will cause injury?
none, just as likely to go up as down.
What is Isometric (geometric) Scaling?
scaling of an object by multiplying every dimension by the same amount.
if you increase the size of an object to maintain isometric dimensions do we also maintain the function?
no, it will not be functionally equivalent.
What is Allometric Scaling?
Scaling an object to maintain the function by changing how it looks.
What are the uses of scaling?
- to understand how structure works
2. to differentiate between differences due to size and differences due to adaptation.
Draw backs of scaling
- regression lines are empirical and just because you get a relationship doesnt mean it represents a requirement to maintain functional significance (the relationship may incorporate both size based requirements and adaptations.
- absolute size may not be relevant
What happens to the surface area to volume ratio as size increases?
it decreases. larger animals have smaller surface area relative to their volume.