BHK Biomechanics 2 — Questions and Answers
Question 1: The term 'moment of inertia' in human movement refers to:
- The speed of joint rotation
- A body segment's resistance to angular acceleration (Correct answer)
- The force produced by a muscle at a joint
- The linear velocity of the center of mass
Correct answer: A body segment's resistance to angular acceleration
Moment of inertia (I = Σmr²) quantifies how mass distribution about an axis resists changes in rotational motion.
Question 2: During projectile motion in sports, which factor does NOT influence the range of a projectile (ignoring air resistance)?
- Projection angle
- Initial projection speed
- Height of projection
- Mass of the projectile (Correct answer)
Correct answer: Mass of the projectile
In the absence of air resistance, range depends on angle, speed, and height of projection but not on the projectile's mass.
Question 3: The mechanical advantage of a lever system is calculated as:
- Effort arm divided by resistance arm (Correct answer)
- Resistance arm divided by effort arm
- Force multiplied by velocity
- Speed ratio times efficiency
Correct answer: Effort arm divided by resistance arm
Mechanical advantage = effort arm / resistance arm; a value >1 means the system amplifies force but reduces speed.
Question 4: Which gait variable is defined as the time elapsed between two consecutive heel strikes of the SAME foot?
- Step length
- Stride length
- Stride time (Correct answer)
- Step time
Correct answer: Stride time
Stride time is the duration of one complete gait cycle, from heel strike of one foot to the next heel strike of that same foot.
Question 5: In a tensile stress-strain curve for biological tissue, the 'toe region' represents:
- Maximum stress before failure
- Elastic deformation proportional to stress
- Straightening of collagen crimp with low stiffness (Correct answer)
- Plastic deformation beyond yield point
Correct answer: Straightening of collagen crimp with low stiffness
The toe region reflects the initial uncrimping of wavy collagen fibers before they become taut and bear load linearly.
Question 6: Which joint in the lower extremity acts as a primary shock absorber during the loading response of gait?
- Hip
- Subtalar joint
- Knee (Correct answer)
- Metatarsophalangeal joints
Correct answer: Knee
Knee flexion (eccentric quadriceps contraction) during the loading response is the primary mechanism for attenuating impact forces.
BHK Biomechanics 2
The term 'moment of inertia' in human movement refers to: