BPK 201 Final UPDATED Exam Questions and CORRECT Answers
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Course
BPK 201
Institution
BPK 201
BPK 201 Final UPDATED Exam Questions
and CORRECT Answers
How is force defined? - CORRECT ANSWER- Quantity that causes motion/deformation
of a body
How can we measure force? - CORRECT ANSWER- 1. balance it against known forces;
2. measure deformation of material of known stiffness; 3. measur...
BPK 201 Final UPDATED Exam Questions
and CORRECT Answers
How is force defined? - CORRECT ANSWER✔✔- Quantity that causes motion/deformation
of a body
How can we measure force? - CORRECT ANSWER✔✔- 1. balance it against known forces;
2. measure deformation of material of known stiffness; 3. measure acceleration of material of
known mass
What is Newton's first law? - CORRECT ANSWER✔✔- If resultant force acting on object of
mass m is zero, structure will not accelerate (object at rest or constant velocity; no
unbalanced forces)
What is Newton's second law? - CORRECT ANSWER✔✔- F=ma; if resultant force acting
on object of mass m is not zero, structure will accelerate in direction of force
What is Newton's third law? - CORRECT ANSWER✔✔- bodies in contact exert equal and
opposite contact forces upon one another (static and dynamic activities)
What affects sarcomere forces? - CORRECT ANSWER✔✔- force per crossbridge, # of
bound crossbridges
How and why does muscle force depend on muscle length? - CORRECT ANSWER✔✔-
Crossbridges have limited stroke (cannot bind to and get pulled off of distant binding sites);
Max force available at intermediate sacromere length
Comment on the force-velocity in muscle shortening (concentric contraction). - CORRECT
ANSWER✔✔- rate of attachment (f) decreases (not enough time for crossbridges to form),
velocity increases, rate of detachment (g) increases (binding sites pulled/pushed away from
myosin very quickly), force in muscle decrease (nmax)
Comment on the force-velocity in muscle lengthening (eccentric contraction). - CORRECT
ANSWER✔✔- rate of attachment (f) unaffected, rate of detachment (g) increases, force
,generation per crossbridge higher as stretching increases (acts like spring), overall nmax
decreases
When is nmax (fraction of myosin forming cross bridges) maximized? - CORRECT
ANSWER✔✔- isometric contraction
What is muscle indeterminacy? - CORRECT ANSWER✔✔- Idea that biomechanical systems
are often indeterminate b/c multiple muscles are supporting the same action, and the load
carried by each muscle is unknown; Number of unknowns (muscle forces) are not equal to
number of equations (force and moment balances)
What is muscle scaling used for? - CORRECT ANSWER✔✔- Method to solve for
indeterminacy
What is the theory of muscle scaling and how does it help solve indeterminacyin
biomechanical systems? - CORRECT ANSWER✔✔- Assumes that stress carried by each
muscle is the same; Force carried by the muscle can be scaled by their physiological cross
sectional area; knowing force of one muscle and both cross sectional areas, you can compute
force of another muscle
What is a limitation of muscle scaling? Give examples. - CORRECT ANSWER✔✔- Several
muscles assumed to be equally activated; Ex. sex differences in muscle activation levels and
motor control strategies: Females/males more susceptible to certain MSK disorders, Females
have more fatigue in biceps while males have more fatigue in trapezius muscle (repetitive
pointing task)
What is physiological cross-sectional area (PCSA)? - CORRECT ANSWER✔✔-
Volume/length
What is optimization? - CORRECT ANSWER✔✔- process of minimizing/maximizing
objective
How is optimization used to solve biomechanically indeterminate systems? - CORRECT
ANSWER✔✔- Many different ways brain can make motion happen. Neurological system
(brain) identifies how load should be distributed between different muscles and chooses the
best solution from set of possibilities;
, How does brain know if initial commands it gave were correct? - CORRECT ANSWER✔✔-
Has copy of commanded muscle forces (efference copy) which is used to predict movement
that would occur with selected forces. Combines it with sensory feedback to readjust force
commands.
Give examples of optimization in biomechanics. - CORRECT ANSWER✔✔- Maximize
speed; minimize energy; maximize stretch
What is static optimization? - CORRECT ANSWER✔✔- Choose objective function that
applies at single point in time
What are examples in which optimization is used in static problems? - CORRECT
ANSWER✔✔- muscle scaling; minimize stress in one muscle; make sure force in one
muscle is less than another
What is dynamic optimization? - CORRECT ANSWER✔✔- Optimize objective function
over entire duration of task
Give an example of dynamic optimization. - CORRECT ANSWER✔✔- Increasing speed
when running a race (speed of entire duration matters)
What is forward dynamics? - CORRECT ANSWER✔✔- Using known force and moment
data to predict motion (linear and angular acceleration)
How is forward dynamics used in biomechanical simulations? - CORRECT ANSWER✔✔-
1. Choose initial positions and velocities
2. Calculate accelerations and forces
3. Compare predicted forces to known forces
What is inverse dynamics? - CORRECT ANSWER✔✔- Using known motion data
(acceleration and mass) to determine forces and moments that caused motion
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