A lever in which the fulcrum is between the applied force and the resistance is classified as a:
A) First class lever
B) Second class lever
C) Third class lever
D) Fourth class lever
Correct answer: A
Explanation: In a first class lever, the fulcrum lies between the effort and the resistance.

​

When a person performs a calf raise, the ankle joint functions as which class of lever?
A) First class
B) Second class
C) Third class
D) Fourth class
Correct answer: B
Explanation: The ball of the foot is the fulcrum, body weight is the resistance, and the Achilles tendon provides the effort, which is second class.

​

In elbow flexion during a biceps curl, the lever system is primarily:
A) First class
B) Second class
C) Third class
D) Fourth class
Correct answer: C
Explanation: The effort is between the fulcrum and the resistance, which defines a third class lever.

​

Torque is mathematically defined as:
A) Force plus displacement
B) Force times perpendicular distance from the axis
C) Mass times acceleration
D) Power divided by time
Correct answer: B
Explanation: Torque equals the product of force and its perpendicular moment arm.

​

If torque remains constant but the moment arm decreases, the required muscle force must:
A) Increase
B) Decrease
C) Remain unchanged
D) Become zero
Correct answer: A
Explanation: With a smaller moment arm, more force is needed to maintain the same torque.

​

True or false: Center of mass can lie outside the physical boundaries of the body.
Correct answer: True
Explanation: Certain body positions can place the center of mass outside the body’s outline.

​

Fill in the blank: The product of mass and acceleration is called ____________________________.
Correct answer: force
Explanation: Newton’s second law defines force as mass times acceleration.

​

Short answer: Define kinematics and give one example of a kinematic variable.
Correct answer: Kinematics is the study of motion without considering forces; examples include position, velocity, or acceleration.
Explanation: It focuses on describing motion, not its causes.

​

Which of the following is an example of a scalar quantity?
A) Force
B) Velocity
C) Displacement
D) Speed
Correct answer: D
Explanation: Scalars have magnitude only; speed lacks direction.

​

Which variable is a vector quantity?
A) Mass
B) Distance
C) Speed
D) Acceleration
Correct answer: D
Explanation: Vectors have magnitude and direction; acceleration has both.

​

The unit of work in the International System of Units is the:
A) Newton
B) Joule
C) Watt
D) Pascal
Correct answer: B
Explanation: One joule equals one newton of force acting through one meter.

​

Power is defined as:
A) Work divided by time
B) Force times distance
C) Mass times velocity
D) Impulse divided by force
Correct answer: A
Explanation: Power measures the rate of doing work.

​

Impulse is equal to:
A) Work times distance
B) Force times time
C) Power divided by acceleration
D) Mass times displacement
Correct answer: B
Explanation: Impulse equals average force multiplied by duration.

​

The law of inertia states that:
A) Force equals mass times acceleration
B) An object at rest stays at rest and an object in motion stays in motion unless acted on by external force
C) For every action there is an equal and opposite reaction
D) Momentum is conserved in a closed system
Correct answer: B
Explanation: This is Newton’s first law.

​

True or false: Linear momentum is calculated as mass times velocity.
Correct answer: True
Explanation: Momentum equals mass times velocity.

​

Fill in the blank: The tendency of an object to resist angular acceleration is called ____________________________.
Correct answer: moment of inertia
Explanation: Moment of inertia depends on mass distribution relative to the axis.

​

Short answer: What is the difference between kinetics and kinematics?
Correct answer: Kinetics studies forces that cause motion; kinematics describes motion without considering forces.
Explanation: They are complementary branches of biomechanics.

​

The ground reaction force is an application of which law?
A) Newton’s first law
B) Newton’s second law
C) Newton’s third law
D) Law of gravitation
Correct answer: C
Explanation: Action–reaction pairs define ground reaction force.

​

If a runner pushes backward on the ground with 500 newtons of force, the ground reaction force forward on the runner is:
A) Less than 500 newtons
B) Greater than 500 newtons
C) Equal to 500 newtons
D) Zero
Correct answer: C
Explanation: Equal and opposite forces act between runner and ground.

​

During a vertical jump, increasing the time spent applying upward force will most directly increase:
A) Impulse
B) Power
C) Center of mass height at rest
D) Efficiency
Correct answer: A
Explanation: Impulse equals force multiplied by time and changes momentum.

​

True or false: Friction always acts in the same direction as motion.
Correct answer: False
Explanation: Friction opposes relative motion or the tendency to move.

​

Fill in the blank: The point about which a body rotates is called the ____________________________.
Correct answer: axis of rotation
Explanation: Angular motion occurs around an axis.

​

Short answer: Define mechanical advantage.
Correct answer: Mechanical advantage is the ratio of the effort arm to the resistance arm that indicates how effectively a lever amplifies force.
Explanation: Larger ratios favor force production.

​

When a figure skater pulls the arms in while spinning, the angular velocity increases because of:
A) Conservation of energy
B) Conservation of angular momentum
C) Increase in external torque
D) Loss of inertia
Correct answer: B
Explanation: Decreasing moment of inertia raises angular velocity if angular momentum is constant.

​

Which of the following best describes an elastic collision?
A) Kinetic energy is lost
B) Kinetic energy is conserved
C) Only momentum is conserved
D) Neither energy nor momentum is conserved
Correct answer: B
Explanation: Elastic collisions conserve both momentum and kinetic energy.

​

The International System of Units unit of pressure is:
A) Newton
B) Pascal
C) Joule
D) Watt
Correct answer: B
Explanation: Pressure equals force per unit area.

​

Center of pressure during standing balance is defined as:
A) The body’s center of mass
B) The point of application of the resultant ground reaction force
C) The midline of the trunk
D) The center of the head
Correct answer: B
Explanation: It is where the net ground force vector acts on the foot.

​

The area under a force–time curve represents:
A) Work
B) Impulse
C) Energy
D) Power
Correct answer: B
Explanation: Force integrated over time yields impulse.

​

Which is an example of angular motion?
A) Runner moving in a straight line
B) Arm rotating at the shoulder
C) A sled sliding downhill
D) A car moving along a highway
Correct answer: B
Explanation: Rotation about an axis defines angular motion.

​

An object launched at twenty meters per second at a forty-five degree angle (ignoring air resistance) has a horizontal velocity component of approximately:
A) Ten meters per second
B) Fourteen point one meters per second
C) Twenty meters per second
D) Twenty-eight point three meters per second
Correct answer: B
Explanation: Horizontal speed equals initial speed times cosine forty-five degrees.

​

True or false: Kinetic energy increases with the square of velocity.
Correct answer: True
Explanation: Kinetic energy equals one half mass times velocity squared.

​

Fill in the blank: Work equals force multiplied by ____________________________.
Correct answer: displacement
Explanation: Work is done when a force causes displacement.

​

Short answer: Define static equilibrium.
Correct answer: Static equilibrium occurs when an object is at rest with net force and net torque both equal to zero.
Explanation: Both translational and rotational balances are required.

​

The slope of a displacement–time graph represents:
A) Acceleration
B) Velocity
C) Force
D) Work
Correct answer: B
Explanation: Change of displacement with respect to time equals velocity.

​

The slope of a velocity–time graph represents:
A) Displacement
B) Acceleration
C) Work
D) Impulse
Correct answer: B
Explanation: Change of velocity with respect to time equals acceleration.

​

If two objects with different masses are dropped from the same height (ignoring air resistance), they:
A) Hit at different times
B) Hit at the same time
C) Accelerate at different rates
D) Stop midair
Correct answer: B
Explanation: They share the same gravitational acceleration.

​

True or false: Stability increases when the line of gravity falls well inside the base of support.
Correct answer: True
Explanation: Greater margin within the base improves stability.

​

Fill in the blank: The resistance to changes in linear motion is called ____________________________.
Correct answer: inertia
Explanation: Inertia reflects mass and resists acceleration.

​

Short answer: What is the relationship between force and momentum?
Correct answer: Force equals the time rate of change of momentum.
Explanation: This is a form of Newton’s second law.

​

During a sprint start, pushing harder against the blocks increases:
A) Angular displacement
B) Moment of inertia
C) Momentum
D) Center of pressure range
Correct answer: C
Explanation: Greater force over time increases the runner’s momentum.

​

A vector is fully described by:
A) Magnitude only
B) Magnitude and direction
C) Speed and distance
D) Work and energy
Correct answer: B
Explanation: Vectors require both magnitude and direction.

​

True or false: Increasing the radius of rotation increases the moment of inertia about that axis.
Correct answer: True
Explanation: Mass farther from the axis increases resistance to angular acceleration.

​

Short answer: Define joint moment.
Correct answer: A joint moment is the rotational effect of forces acting about a joint, equal to force times its moment arm.
Explanation: It is a torque at a joint.

​

Fill in the blank: The time integral of power equals ____________________________.
Correct answer: work
Explanation: Work is the accumulation of power over time.

​

In landing from a jump, increasing knee and hip flexion generally:
A) Increases peak impact force
B) Decreases peak impact force by lengthening deceleration time
C) Leaves peak impact force unchanged
D) Eliminates ground reaction force
Correct answer: B
Explanation: A longer stopping time reduces force for the same impulse.

​

When throwing, which sequencing best promotes high end-point speed?
A) Distal-to-proximal
B) Proximal-to-distal
C) Simultaneous
D) Random
Correct answer: B
Explanation: Energy is transferred from larger proximal segments to smaller distal segments.

​

Which statement about static friction is correct?
A) It is independent of normal force
B) It increases with the normal force until the limit is reached
C) It does not depend on surface materials
D) It always equals kinetic friction
Correct answer: B
Explanation: The maximum static friction equals the coefficient times the normal force.

​

True or false: Mechanical work can be negative when a force acts opposite to displacement.
Correct answer: True
Explanation: Eccentric muscle action performs negative work on the external load.

​

Fill in the blank: The distance of the line of action of a force from the axis of rotation, measured perpendicularly, is the ____________________________.
Correct answer: moment arm
Explanation: Moment arm determines torque for a given force.

​

Short answer: What does conservation of mechanical energy mean for a system with no nonconservative work?
Correct answer: The sum of kinetic and potential energy remains constant.
Explanation: Without losses, energy transforms between forms.

​

In gait analysis, the early distinct peak in vertical ground reaction force for rearfoot striking typically represents the:
A) Propulsive peak
B) Impact peak
C) Midstance trough
D) Toe-off dip
Correct answer: B
Explanation: Heel strike creates a transient impact peak before the active peak.

​

Sampling a very fast motion at too low a frequency produces:
A) Smoothing only
B) Aliasing
C) No effect
D) Better resolution
Correct answer: B
Explanation: Under-sampling misrepresents true frequency content.

​

Using an excessively low cutoff in low-pass filtering of kinematics will:
A) Preserve all true movement content
B) Over-smooth and remove meaningful signal
C) Increase noise
D) Create artificial spikes
Correct answer: B
Explanation: Too-aggressive filtering attenuates real motion.

​

True or false: Center of pressure migration forward during stance indicates loading toward the forefoot.
Correct answer: True
Explanation: The center of pressure path moves toward the metatarsal heads as the stance progresses.

​

Fill in the blank: The study of forces in fluids and their effects on bodies is called ____________________________.
Correct answer: fluid mechanics
Explanation: It includes drag, lift, and flow behavior.

​

Short answer: Define Reynolds number qualitatively.
Correct answer: Reynolds number describes the ratio of inertial to viscous effects and indicates whether flow is more laminar or turbulent.
Explanation: It helps anticipate flow regime and drag type.

​

Aerodynamic drag in typical outdoor running conditions increases approximately with the:
A) Square root of velocity
B) Square of velocity
C) Cube of velocity
D) Fourth power of velocity
Correct answer: B
Explanation: Form and pressure drag scale roughly with velocity squared.

​

A force applied away from the center of mass of a rigid body generally causes:
A) Only translation
B) Only rotation
C) Both translation and rotation
D) No motion
Correct answer: C
Explanation: The net effect is a linear acceleration of the center of mass and an angular acceleration about it.

​

True or false: The work–energy principle states that the net work done on a body equals its change in kinetic energy.
Correct answer: True
Explanation: Net external work changes kinetic energy.

​

Fill in the blank: The ratio of output work to input work is called ____________________________.
Correct answer: efficiency
Explanation: It quantifies how well input energy becomes useful output.

​

Short answer: What does a positive joint power indicate during movement?
Correct answer: Positive joint power indicates net concentric action where energy is generated.
Explanation: Negative power indicates energy absorption (eccentric action).

​

Which change will reduce the external knee extensor moment in a back squat?
A) Allowing the knees to travel far forward
B) Keeping the shanks more vertical
C) Narrowing the stance only
D) Looking upward
Correct answer: B
Explanation: Reducing the horizontal distance from the knee to the load lowers the knee moment.

​

Compared with a back squat, a front squat typically produces a larger:
A) Hip extensor moment
B) Knee extensor moment
C) Ankle plantarflexor moment
D) Elbow flexor moment
Correct answer: B
Explanation: The anterior bar position increases the knee moment arm and reduces the hip moment arm.

​

True or false: For a given horizontal speed, a shorter ground contact time in running generally indicates greater leg spring stiffness.
Correct answer: True
Explanation: Stiffer leg behavior shortens contact time at the same speed.

​

Fill in the blank: The linear speed of a point on a rotating segment equals angular velocity times ____________________________.
Correct answer: radius of rotation
Explanation: v = ω × r.

​

Short answer: Define inverse dynamics in biomechanics.
Correct answer: Inverse dynamics estimates joint moments and joint powers from measured motion and external forces using equations of motion.
Explanation: It works backward from kinematics and ground forces.

​

The most stable stance is achieved by:
A) Raising the center of mass and narrowing the base
B) Lowering the center of mass and widening the base
C) Closing the eyes only
D) Turning the head
Correct answer: B
Explanation: Lower and wider support increases the stability margin.

​

In a sit-to-stand task, moving the trunk forward before lifting primarily:
A) Reduces hip extensor moment
B) Shifts the center of mass forward to reduce required knee extensor moment
C) Eliminates ground reaction force
D) Increases ankle dorsiflexor moment only
Correct answer: B
Explanation: Forward lean places the center of mass over the feet, easing knee extension demands.

​

True or false: Negative work at the knee during landing indicates energy absorption by the knee extensors.
Correct answer: True
Explanation: Eccentric quadriceps action absorbs energy, shown as negative joint power.

​

Fill in the blank: The height reached by a projectile (neglecting air resistance) depends on initial vertical velocity and ____________________________.
Correct answer: gravitational acceleration
Explanation: Gravity decelerates the upward motion.

​

Short answer: Why does a long baseball bat feel “heavier” to swing than a short one of the same mass?
Correct answer: More mass is distributed farther from the axis, increasing moment of inertia and resisting angular acceleration.
Explanation: Swing difficulty relates to rotational inertia, not just mass.

​

Which choice best increases impulse during a countermovement jump without changing peak force?
A) Shorten push-off time
B) Lengthen push-off time
C) Reduce countermovement depth
D) Reduce ankle range of motion
Correct answer: B
Explanation: Increasing contact time increases the area under the force–time curve.

​

A bicycle cleat moved posteriorly on the shoe most directly:
A) Increases ankle plantarflexor moment
B) Decreases ankle plantarflexor moment
C) Increases knee extensor moment
D) Eliminates hip moment
Correct answer: B
Explanation: A posterior cleat shortens the forefoot lever, reducing ankle moment.

​

True or false: The center of mass of a system moves as if all mass and external forces act at that point.
Correct answer: True
Explanation: External forces determine center of mass motion regardless of internal forces.

​

Fill in the blank: The ratio of stress to strain in the linear region of a material’s behavior defines ____________________________.
Correct answer: Young’s modulus
Explanation: It quantifies stiffness.

​

Short answer: Define viscoelasticity in biological tissues.
Correct answer: Viscoelastic tissues exhibit time-dependent strain where response depends on both elastic storage and viscous flow.
Explanation: They show creep, stress relaxation, and hysteresis.

​

In a simple bending situation, tensile stress occurs on the side of the beam that is:
A) Concave
B) Convex
C) Neutral axis
D) Center of mass
Correct answer: B
Explanation: Fibers on the convex side are stretched.

​

Which change most increases rotational kinetic energy for a given angular velocity?
A) Decreasing moment of inertia
B) Increasing moment of inertia
C) Decreasing mass only
D) Reducing radius of rotation
Correct answer: B
Explanation: Rotational kinetic energy equals one half moment of inertia times angular velocity squared.

​

True or false: Lift force can be generated on an object moving through a fluid even if it is symmetric, if the flow is angled.
Correct answer: True
Explanation: Angle of attack can create pressure differences and lift.

​

Fill in the blank: The tendency of a material to return to its original length after unloading is called ____________________________.
Correct answer: elasticity
Explanation: Elastic materials recover shape when stress is removed.

​

Short answer: What does a larger mechanical advantage (>1) imply for a lever?
Correct answer: Less effort force is needed to balance or move a given resistance.
Explanation: A longer effort arm relative to resistance arm favors force.

​

During a deadlift, keeping the load close to the body primarily:
A) Increases spinal extensor moment
B) Decreases spinal extensor moment by reducing the horizontal distance to the spine
C) Increases knee extensor moment
D) Eliminates hip extensor moment
Correct answer: B
Explanation: A shorter moment arm about the spine reduces required extensor torque.

​

The coefficient of restitution between a ball and the ground primarily reflects:
A) Surface roughness only
B) Energy loss during impact
C) Air density
D) Spin axis
Correct answer: B
Explanation: It indicates how much kinetic energy is conserved in a collision.

​

True or false: In static equilibrium, the sum of clockwise and counterclockwise torques must be equal.
Correct answer: True
Explanation: Net torque must be zero.

​

Fill in the blank: The center line about which normal bending stress changes sign in a beam is the ____________________________.
Correct answer: neutral axis
Explanation: Above the neutral axis stress is one sign; below it is the opposite.

​

Short answer: Why does smoothing noisy coordinate data with an appropriate low-pass filter improve inverse dynamics?
Correct answer: It reduces amplified noise in acceleration and force estimates that would contaminate joint moments.
Explanation: Differentiation magnifies high-frequency noise.

​

Which factor most strongly increases buoyant force on a swimmer?
A) Higher speed
B) Greater fluid density
C) Darker suit color
D) Lower body mass
Correct answer: B
Explanation: Buoyant force equals the weight of displaced fluid.

​

A runner who increases step frequency while keeping running speed constant will:
A) Increase step length
B) Decrease step length
C) Keep step length the same
D) Stop bouncing vertically
Correct answer: B
Explanation: Speed equals frequency times length; higher frequency lowers length at constant speed.

​

True or false: Negative joint power indicates energy generation.
Correct answer: False
Explanation: Negative power indicates energy absorption (eccentric action).

​

Fill in the blank: The maximum static friction force before sliding occurs equals the coefficient of static friction times the ____________________________.
Correct answer: normal force
Explanation: This is the limiting friction condition.

​

Short answer: Define center of mass in simple terms.
Correct answer: Center of mass is the weighted average location of all mass in a system where external forces effectively act.
Explanation: Internal forces do not change its motion.

​

When balancing a seesaw, a lighter person can balance a heavier person by:
A) Moving closer to the fulcrum
B) Moving farther from the fulcrum
C) Standing on the heavier side
D) Increasing friction
Correct answer: B
Explanation: A longer moment arm can compensate for smaller force.

​

During a push-up, shifting body weight forward toward the hands primarily increases:
A) Elbow flexor moment
B) Shoulder flexor moment
C) Shoulder extensor moment
D) Hip extensor moment
Correct answer: B
Explanation: The horizontal distance from the shoulder to the line of action increases, raising shoulder flexor torque.

​

True or false: The power produced during a movement is maximal when both force and velocity are at their individual maxima.
Correct answer: False
Explanation: Power peaks at an intermediate combination of force and velocity.

​

Fill in the blank: A measurement error that is consistent and directional across trials is called ____________________________ error.
Correct answer: systematic
Explanation: Systematic error biases measurements in one direction.

​

Short answer: Why is choosing an appropriate sampling frequency essential for motion capture?
Correct answer: Sampling must be at least twice the highest signal frequency to avoid aliasing and to represent the motion accurately.
Explanation: This is the Nyquist requirement.

​

The best way to increase range of a projectile that must be released higher than it lands (for example, a shot put) is often to:
A) Use a forty-five degree angle regardless
B) Use a launch angle less than forty-five degrees
C) Use a launch angle greater than sixty degrees
D) Decrease release speed
Correct answer: B
Explanation: When release height exceeds landing height, the optimal angle is less than forty-five degrees.

​

A person carrying a load on one side can reduce trunk muscle demand by:
A) Leaning away from the load
B) Leaning slightly toward the load
C) Walking faster
D) Holding the breath
Correct answer: B
Explanation: Leaning toward the load reduces its moment arm about the spine.

​

True or false: Series elastic components in muscle–tendon units store and return mechanical energy during stretch–shorten cycles.
Correct answer: True
Explanation: Elastic tissues absorb and return energy, aiding performance.

​

Fill in the blank: The product of force and velocity at a joint equals joint ____________________________.
Correct answer: power
Explanation: Joint power indicates energy generation or absorption.

​

Short answer: What does co-contraction of antagonistic muscles around a joint do to joint stiffness?
Correct answer: Co-contraction increases joint stiffness and stability by raising combined muscle forces.
Explanation: It resists perturbations but may increase energy cost.

​

The plane in which shoulder abduction primarily occurs is the:
A) Sagittal plane
B) Frontal plane
C) Transverse plane
D) Oblique plane
Correct answer: B
Explanation: Abduction and adduction are frontal plane motions.

​

Which adjustment reduces the external knee extensor moment the most during stair descent?
A) Keeping the center of mass far behind the knee
B) Reducing forward knee travel over the toes
C) Using a handrail to reduce net external load
D) Increasing step length only
Correct answer: C
Explanation: Offloading reduces the ground reaction force and its moment arm.

​

True or false: A rigid body can experience zero net force yet nonzero torque.
Correct answer: True
Explanation: Force couple systems produce pure rotation without translation.

​

Fill in the blank: The horizontal distance from the ground reaction force vector to a joint center defines the joint ____________________________ for that force.
Correct answer: moment arm
Explanation: It determines the external moment from that force.

​

Short answer: Why does a long landing mat reduce injury risk in gymnastics?
Correct answer: It increases stopping time and distance, reducing peak force for the same impulse.
Explanation: Lower peak deceleration lowers tissue stress.

​

In cycling, moving the saddle forward generally:
A) Increases hip extensor moment and decreases knee extensor moment
B) Decreases hip extensor moment and increases knee extensor moment
C) Decreases both hip and knee moments
D) Increases ankle plantarflexor moment only
Correct answer: B
Explanation: The knee’s horizontal distance to the line of action increases while the hip’s decreases.

​

When a diver tucks midair, the primary biomechanical effect is to:
A) Increase moment of inertia and slow rotation
B) Decrease moment of inertia and speed rotation
C) Stop rotation
D) Change linear momentum
Correct answer: B
Explanation: With near-zero external torque, decreasing inertia increases angular velocity.

​

True or false: The net external moment at a joint can be zero even when large internal muscle forces are present.
Correct answer: True
Explanation: Opposing internal forces can balance external moments.

​

Fill in the blank: The path traced by the center of pressure under the foot during stance is often called the center of pressure ____________________________.
Correct answer: trajectory
Explanation: It shows the time-varying location of resultant ground force.

​

Short answer: Define static friction qualitatively.
Correct answer: Static friction resists the start of sliding between two surfaces up to a maximum proportional to normal force.
Explanation: Beyond the limit, sliding occurs and kinetic friction acts.

​

Which combination best increases jump height?
A) Greater impulse and higher takeoff speed
B) Shorter force application time with the same force
C) Lower takeoff speed with higher angle
D) Reduced countermovement
Correct answer: A
Explanation: Jump height depends on takeoff velocity, which increases with impulse.

​

A sprinter accelerates fastest when the ground reaction force vector has a large:
A) Downward vertical component only
B) Forward horizontal component
C) Backward horizontal component
D) Upward vertical component only
Correct answer: C
Explanation: A backward push yields a forward reaction that accelerates the sprinter.

​

True or false: A body in purely translational equilibrium can still rotate if torques are present.
Correct answer: False
Explanation: Translational equilibrium requires net force zero; rotation would require nonzero net torque.

​

Fill in the blank: The rotational analog of mass is ____________________________.
Correct answer: moment of inertia
Explanation: It resists angular acceleration.

​

Short answer: Why is it advantageous to keep a barbell over the midfoot during a deadlift?
Correct answer: It minimizes the horizontal distance between the line of action of the load and the joints, reducing external moments and required muscle torques.
Explanation: Shorter moment arms reduce effort.

​

Which factor most decreases air resistance on a cyclist?
A) Wearing loose clothing
B) Lowering frontal area and improving posture
C) Using heavier wheels
D) Raising the head
Correct answer: B
Explanation: Drag depends strongly on projected area and shape.

​

During level walking, the center of mass path is best described as:
A) A flat line
B) A smooth sinusoidal-like path in three dimensions
C) A series of step changes
D) A random pattern
Correct answer: B
Explanation: It oscillates vertically and side-to-side with each step.

​

True or false: The magnitude of the buoyant force equals the weight of displaced fluid.
Correct answer: True
Explanation: This is Archimedes’ principle.

​

Fill in the blank: The rotational work done by a torque equals torque times ____________________________.
Correct answer: angular displacement
Explanation: Rotational work is analogous to force times linear displacement.

​

Short answer: Why is angular momentum often used to analyze whole-body rotation in midair?
Correct answer: With negligible external torque, angular momentum is conserved, simplifying analysis of shape changes.
Explanation: Shape changes alter inertia and angular velocity while conserving momentum.

​

In a bench press, widening the grip typically:
A) Decreases shoulder abduction moment
B) Increases shoulder abduction moment
C) Eliminates elbow extensor moment
D) Increases hip extensor moment
Correct answer: B
Explanation: A wider hand placement increases the shoulder moment arm.

​

Which parameter most directly determines the peak centripetal force during a turn while running a curve?
A) Body mass and curve radius only
B) Speed squared divided by curve radius
C) Air density
D) Step frequency only
Correct answer: B
Explanation: Centripetal force equals mass times speed squared divided by radius.

​

True or false: The same external torque can cause different angular accelerations if moments of inertia differ.
Correct answer: True
Explanation: Angular acceleration equals torque divided by moment of inertia.

​

Fill in the blank: The study of how loads are transferred through bones and joints under static conditions is called ____________________________.
Correct answer: statics
Explanation: Statics examines forces in systems at rest.

​

Short answer: What happens to joint reaction forces when co-contraction increases at a joint?
Correct answer: Joint reaction forces usually increase because opposing muscles both pull across the joint.
Explanation: Higher internal forces compress the joint more.

​

Which factor most reduces peak landing force when step height cannot change?
A) Reduce knee flexion
B) Increase landing time by flexing hips and knees
C) Stiffen the ankle
D) Land on the heels with locked knees
Correct answer: B
Explanation: Increasing deceleration time lowers peak force for a given impulse.

​

A runner experiences the greatest shoe–ground friction requirement during:
A) Mid-flight
B) Initial braking phase of stance
C) Toe-off only
D) Mid-stance vertical peak
Correct answer: B
Explanation: Braking requires large horizontal shear forces.

​

True or false: A material that exhibits hysteresis dissipates energy during loading–unloading cycles.
Correct answer: True
Explanation: The area between loading and unloading curves reflects energy loss.

​

Fill in the blank: The vertical line from the center of mass to the ground is called the line of ____________________________.
Correct answer: gravity
Explanation: It indicates where weight acts relative to the base of support.

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Short answer: Define degrees of freedom for a rigid body in three-dimensional space.
Correct answer: A free rigid body has six degrees of freedom: three translations and three rotations.
Explanation: Constraints reduce available degrees.

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During a kettlebell swing, the peak external moment at the hip occurs primarily when:
A) The bell is at the top of the arc
B) The bell passes near mid-swing with the greatest horizontal distance from the hip
C) The bell is on the ground
D) The bell is above the head
Correct answer: B
Explanation: The external moment depends on the horizontal distance to the line of action of the weight.

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Which change most increases the risk of aliasing in motion capture?
A) Increasing sampling frequency
B) Decreasing sampling frequency
C) Using a wider lens
D) Filtering after capture
Correct answer: B
Explanation: Lower sampling increases aliasing risk for fast motions.

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True or false: For a freely rotating figure skater in air, internal muscle actions can change angular momentum.
Correct answer: False
Explanation: Without external torque, internal actions cannot change total angular momentum.

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Fill in the blank: The slope of the stress–strain curve in the linear region represents material ____________________________.
Correct answer: stiffness
Explanation: Stiffness is quantified by Young’s modulus.

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Short answer: Why might a runner choose a higher step frequency at the same speed to reduce injury risk?
Correct answer: Higher frequency shortens stride, lowering vertical oscillation and peak braking forces per step.
Explanation: It reduces loading rates.

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A baseball pitcher increases ball speed mainly by:
A) Increasing ball mass
B) Increasing release speed through proximal-to-distal sequencing and long acceleration path
C) Decreasing stride length
D) Reducing trunk rotation
Correct answer: B
Explanation: Effective sequencing and longer lever paths raise end-point velocity.

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Which statement about joint power is correct?
A) Positive joint power indicates absorption
B) Negative joint power indicates generation
C) Positive joint power indicates generation
D) Joint power does not relate to muscle action
Correct answer: C
Explanation: Positive power reflects net concentric action; negative reflects eccentric.

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True or false: Inverse dynamics requires both kinematic data and external force data to estimate joint moments accurately.
Correct answer: True
Explanation: Equations of motion need accelerations and external forces.

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Fill in the blank: The relationship showing that force capacity declines as shortening velocity increases is called the force–____________________________ relationship.
Correct answer: velocity
Explanation: It describes the trade-off between force and speed in muscle.

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Short answer: Why does keeping the head and torso upright during a squat increase the knee extensor demand compared with a forward-leaning technique?
Correct answer: A more upright trunk increases the horizontal distance from the knee to the line of action of the load, increasing the knee moment arm.
Explanation: Moment arms set external joint moments.