Final Exam Biomechnics KIN 3309 U of H
In circulatory systems, it has been observed that when a vessel bifurcates, the two resulting vessels have radii of approximately _____ that of the parent vessel.
80%
How much force must be applied by a kicker to give a stationary 2 kg ball an acceleration of 40 m/s2?
80N
Which of the following statements about the action potential of a motor neuron is true?
A) It is a change in membrane potential that propagates along a membrane. B) An action potential is an "all-or-none" response. C) An action potential requires sodium and potassium ions to move across the neuron membrane. NOT TRUE (The strength of the signal diminishes as it travels along the neuron.)
Which of the following is true about relative velocity?
A) Relative velocity is the difference between an object's velocity and the surrounding fluid's velocity. B) Relative velocity is how fast the fluid moves past an object. (I.e., how fast the fluid "appears" to be moving to the object.) C) For a person running in still air, the relative velocity is the same as the person's running velocity. NOT TRUE (Relative velocity will be lower for a person running into the wind than for a person running with the wind.)
A baseball is thrown across a field at an angle of 30° and from a height of 2m. The ball lands on the ground. Which of the following statement is true?
The baseball traveled farther than it would have if it had been caught at a height of 2m.
A baseball and a lighter, foam ball of the same size and shape as a baseball are thrown with the same initial conditions. Which of the following statements is true?
The baseball will experience less acceleration from fluid dynamic forces.
Which of the following statement about reflexes is true?
They are involuntary responses to stimuli.
In what direction is centripetal force?
Toward the center of the turn.
What muscle fiber type would an endurance runner use during the majority of a race?
Type I (slow-oxidative)
Select the row with the correct angular analogs of the following linear parameters:
linear velocity force mass angular velocity torque moment of inertia
If the applied muscle force remains constant, what other variable can be altered to increase the torque that the muscle creates around a joint?
moment arm
An object that is denser than water will _____ if submerged in water and then released.
move downward (sink)
The knee joint
moves primarily in flexion and extension.
Electromyography (EMG) measures:
muscle activity
If angular velocity is decreasing, angular acceleration must be:
negative
Lift acts
perpendicular to the relative motion of an object moving through a fluid.
Which is the most important factor in determining the rate of fluid flow through a pipe? (Assuming laminar flow.)
pipe radius
If velocity is increasing, acceleration must be:
positive
What is described by this equation: θthigh-abs - θtrunk-abs ?
relative hip angle
Changing which factor below has the greatest effect on the dynamic fluid force?
relative velocity
Which of the following would minimize the effects of dynamic fluid forces on a runner on a windy day?
running with (in the same direction as) the wind
A somersault, such as the one depicted here, occurs in which plane
sagittal
The most efficient circulatory system will have the same _____ throughout the system.
shear stress at vessel walls
Which of the following is NOT part of the central nervous system (CNS)?
skull
Velocity is:
the change in position over time.
A relative angle is:
the difference between two angles.
Choose the row that shows the correct units for each quantity:
weight mass acceleration work Newtons kilograms m/s² Joules (N·m)
Surface drag is
friction of fluid molecules against an object.
A projectile is an object that is acted on by:
gravity and air resistance (which we often ignore)
A soccer ball is kicked with an initial angle of about 45°. Which of the following would increase the horizontal distance traveled by the soccer ball? (All else remaining equal. Assume air resistance is negligible.)
greater initial horizontal velocity
The elbow (ulnarhumeral articulation) is an example of a _____ joint.
hinge
The density of air is affected by what?
humidity, temperature, pressure
Which of the following surfaces would have the lowest coefficient of friction?
ice
If a cyclist increases velocity, momentum _____.
increase
Which structure separates two adjacent vertebral bodies?
intervertebral disc
Compared to cancellous ("spongy") bone, cortical ("compact") bone
is denser
For a neuron, myelin
is wrapped around the axon.
ABduction of the leg would result in
laterally extending the leg.
Compared to contracting while at its resting length ("L0"), a muscle contracting while at a much shorter length can produce _____ force. (All else being equal.)
less
f a muscle shortens more rapidly, it can produce _____ force. (All else being equal.)
less
A fluid with a lower viscosity would be _____ to stir, compared to a fluid with higher viscosity. (All else being equal.)
less difficult
What is the acceleration of a runner whose speed changes from 7 m/s to 9 m/s in 4 seconds?
0.5 m/s²
A person with heart disease has blockage in an artery that results in a radius 30% of the original radius. What is the flow rate through this blocked artery as a percent of the rate prior to the blockage?
0.8%
A person walks 2 km east, 2 km west, 3 km north, and 2 km south. What is the final displacement?
1 km north
A therapist examines the range of motion of an athlete's elbow joint. At full extension, the angle between the forearm and upper arm is 170°. At full flexion, the angle between the forearm and upper arm is 45°. What is the range of motion of the elbow joint?
125°
The healthy shoulder joint (glenohumeral joint) has how many degrees of freedom?
3 degrees
The normal force experienced by a box with a mass of 30 kg, resting on a level surface, is:
300N
A table-tennis ball spins as it travels through the air. Which of the following statements is true?
A) The curve of the ball will depend on the direction of the ball's spin. B) The spin of the ball changes the velocity of the fluid around it. C) The curve of the ball is the result of a difference between the force acting on opposite sides of the ball. NOT TRUE (The pressure of the fluid remains the same at all points around the ball.)
Which of the following is a consequence of the no-slip condition?
A) The velocity of a fluid at a surface is zero (or very close to zero). B) Boundary layers. NOT (Clean fan blades.) D) Surface drag.
Which of the following statements is true of cartilage?
A) firm, yet flexible B) distributes the load in a joint C) increases joint stability NOT TRUE (heals quickly because it has its own blood supply)
A dynamic force is affected by which of the following?
A) fluid density B) object shape (e.g., surface area) C) relative velocity
Which of the following is a dynamic fluid force?
A) lift NOT (buoyant force) C) form drag D) surface drag
The position of the pelvis affects the position of
A) the trunk B) the legs
Which bone is part of the ankle joint
A) tibia B) fibula C) talus NOT PART(fifth metatarsal)
What is the moment of inertia?
An object's resistance to change in angular motion.
Which of the following are true about energy?
B) Energy is the capacity to do work. C) An object in motion has energy. D) Energy can be converted between different types of energy.
Which of the following statements about the resting membrane potential of a motor neuron is true?
B) It is due to differences in ion concentrations on the inside vs. outside of the neuron. C) It is maintained actively (i.e., it requires energy). D) It involves sodium and potassium ions.
The lumbar region of the spine
B) allows more flexion-extension than other regions of the spine. C) normally shows lordosis (an anterior curvature). D) has more robust vertebrae than other regions of the spine.
The amount of strain an object experiences when a stress is applied
B) depends on the amount of stress applied. C) is calculated using the change in length and the original length. D) depends on the object's elastic (Young's) modulus.
Muscles with a pennate fiber arrangement
B) have a greater physiological cross-sectional area (and therefore, potential for force production) for a given volume, compared to a parallel-fibered muscle. C) have fibers arranged at an angle relative to their attachment points. D) include the gastrocnemius, semimembranosis, and deltoid.
Fluids
B) include gases and liquids. C) resist the movement of objects through them. D) have the properties of density and viscosity.
More mobile joints tend to be
B) more complicated. C) less stable. D) injured more frequently
Which of the following could cause injury to a bone or joint?
B) sudden, high stress C) moderate stress repeatedly applied D) stress applied in an unusual orientation
Which of the following quantities is a vector?
NOT A VECTOR (mass) B) displacement C) acceleration D) force
Angular displacement is:
a change in angular position and the direction of the change
Two runners in different lanes of the track travel at the same angular velocity around the curve of the track. The runner in the outer lane travels at _____ linear velocity.
a greater
A figure skater performs a double spin (two complete revolutions) in the same amount of time as a triple spin (three complete revolutions). The double spin had _____ angular velocity.
a lower
viscosity is:
a measure of a fluid's resistance to flow.
Consider the wheel of a stationary bicycle. Compared to a point on the edge of the wheel, a point on the wheel near the axle will travel _____ linear distance.
a shorter
When calculating how far a projectile travels, we often ignore the effects of air resistance. If we were to account for air resistance (dynamic fluid forces), we would find that a ball thrown in still air travels _____ we would otherwise predict.
a shorter distance than
The sliding filament model of muscle contraction states that
actin and myosin filaments slide past each other during contraction.
Synovial fluid
acts as a lubricant when not under pressure, but as a shock-absorber when under pressure.
Where does the fluid in a pipe have the greatest velocity? (Assume the flow is laminar and far from the entrance of the pipe.)
at the center of the pipe.
A person performs a roundhouse kick. If the person performs another kick wherein the leg has the same moment of inertia and a greater angular acceleration, the torque produced will _____.
be greater
The biceps produces a certain force (Fm) in three different positions shown below. The torque generated by the biceps is greatest in which of the following positions?
bicep and forearm at 90 degree angle
Select the sequence wherein the elements are arranged from largest/most inclusive to smallest/most specific:
compartment, individual muscle, fascicle, muscle fiber, sarcomere
Ligaments
connect bone to bone
A person's ankle is always ________ relative to the knee
distal
A figure skater is performing a spin with outstretched arms. The skater then brings in the arms, which _____ angular momentum. (Assume friction and air resistance are negligible.)
does not change
A person is flexing the elbow to lift a weight with the hand. Which parts of the system correspond to which elements of a lever? (Choose the correct row.)
effort resistance fulcrum bicep muscles force weight elbow joint
Weight is
equal to mass times gravity.
Bernoulli's principle is
faster-moving fluids exert less pressure (laterally) than do slower-moving fluids.
Buoyancy is a consequence of
fluid pressure.
Stress is
the force applied to an object, divided by the area over which the force is applied.
Density is:
the mass of an object or fluid divided by its volume.
The boundary layer is:
the region near a surface where fluid velocity is less than the velocity far away from the surface.
Form drag is
the result of the impact of fluid molecules on an object.
The magnitude of the buoyant force acting on an object is:
the weight of the volume of fluid displaced by the object.