SPHE 324 Week 3 Exam:
Biomechanical Concepts and
Joint Actions
Total Points: 100 | Time Limit: 90 Minutes
1. Which of the following best defines angular acceleration?
• A) The change in linear velocity over time
• B) The rate of change of angular velocity
• C) The total angular displacement divided by time
• D) The product of angular velocity and radius
Answer: B) The rate of change of angular velocity
Rationale: Angular acceleration is the rate at which angular velocity changes over
time. It is measured in radians per second squared (rad/s²) or degrees per second
squared. Option A describes linear acceleration, option C describes average
angular velocity, and option D describes tangential velocity.
2. One radian is approximately equal to:
• A) 45 degrees
• B) 57.3 degrees
• C) 90 degrees
• D) 180 degrees
Answer: B) 57.3 degrees
Rationale: A radian is defined as the angle subtended at the center of a circle by
an arc equal in length to the radius of the circle. Since there are 2π radians in a full
circle (360°), one radian equals 360°/(2π) ≈ 57.3°. This is a fundamental concept in
angular kinematics.
,3. When the scapula's medial border moves inferiorly and the shoulder moves
superiorly, this action is called:
• A) Downward rotation
• B) Upward rotation
• C) Protraction
• D) Retraction
Answer: B) Upward rotation
Rationale: Upward rotation of the scapula occurs when the inferior angle moves
laterally and superiorly, while the glenoid fossa faces upward. The description
given—medial border moving inferiorly and shoulder moving superiorly—is
characteristic of upward rotation, which is essential for full shoulder abduction.
4. Which joint action involves the arm moving toward the midline of the body
in the transverse plane?
• A) Horizontal abduction
• B) Horizontal adduction
• C) Abduction
• D) External rotation
Answer: B) Horizontal adduction
Rationale: Horizontal adduction occurs when the arm moves from a position of
90° abduction toward the midline of the body in the transverse plane. Horizontal
abduction is the opposite movement, where the arm moves away from the midline
in the transverse plane.
5. Eversion is a motion that occurs at which joint?
• A) Shoulder joint
• B) Hip joint
, • C) Subtalar joint
• D) Elbow joint
Answer: C) Subtalar joint
Rationale: Eversion is a frontal plane motion of the foot where the plantar surface
faces laterally (away from the midline). This occurs at the subtalar joint and
involves the calcaneus moving laterally. It is the opposite of inversion and is
important for understanding ankle biomechanics.
6. The ratio of arc length to radius length defines:
• A) Angular velocity
• B) Angular displacement
• C) Radian measure
• D) Linear displacement
Answer: C) Radian measure
Rationale: The radian is defined as the ratio of the arc length (s) to the radius (r): θ
= s/r. When s equals r, the angle is exactly 1 radian. This relationship is
fundamental to understanding angular kinematics and the relationship between
linear and angular motion.
7. Which of the following describes lateral rotation of the hip or shoulder
joint?
• A) Internal rotation
• B) External rotation
• C) Horizontal adduction
• D) Horizontal abduction
Answer: B) External rotation
Rationale: External rotation (also called lateral rotation) involves rotating the limb
outward, away from the midline. At the shoulder, this means the palm faces
Biomechanical Concepts and
Joint Actions
Total Points: 100 | Time Limit: 90 Minutes
1. Which of the following best defines angular acceleration?
• A) The change in linear velocity over time
• B) The rate of change of angular velocity
• C) The total angular displacement divided by time
• D) The product of angular velocity and radius
Answer: B) The rate of change of angular velocity
Rationale: Angular acceleration is the rate at which angular velocity changes over
time. It is measured in radians per second squared (rad/s²) or degrees per second
squared. Option A describes linear acceleration, option C describes average
angular velocity, and option D describes tangential velocity.
2. One radian is approximately equal to:
• A) 45 degrees
• B) 57.3 degrees
• C) 90 degrees
• D) 180 degrees
Answer: B) 57.3 degrees
Rationale: A radian is defined as the angle subtended at the center of a circle by
an arc equal in length to the radius of the circle. Since there are 2π radians in a full
circle (360°), one radian equals 360°/(2π) ≈ 57.3°. This is a fundamental concept in
angular kinematics.
,3. When the scapula's medial border moves inferiorly and the shoulder moves
superiorly, this action is called:
• A) Downward rotation
• B) Upward rotation
• C) Protraction
• D) Retraction
Answer: B) Upward rotation
Rationale: Upward rotation of the scapula occurs when the inferior angle moves
laterally and superiorly, while the glenoid fossa faces upward. The description
given—medial border moving inferiorly and shoulder moving superiorly—is
characteristic of upward rotation, which is essential for full shoulder abduction.
4. Which joint action involves the arm moving toward the midline of the body
in the transverse plane?
• A) Horizontal abduction
• B) Horizontal adduction
• C) Abduction
• D) External rotation
Answer: B) Horizontal adduction
Rationale: Horizontal adduction occurs when the arm moves from a position of
90° abduction toward the midline of the body in the transverse plane. Horizontal
abduction is the opposite movement, where the arm moves away from the midline
in the transverse plane.
5. Eversion is a motion that occurs at which joint?
• A) Shoulder joint
• B) Hip joint
, • C) Subtalar joint
• D) Elbow joint
Answer: C) Subtalar joint
Rationale: Eversion is a frontal plane motion of the foot where the plantar surface
faces laterally (away from the midline). This occurs at the subtalar joint and
involves the calcaneus moving laterally. It is the opposite of inversion and is
important for understanding ankle biomechanics.
6. The ratio of arc length to radius length defines:
• A) Angular velocity
• B) Angular displacement
• C) Radian measure
• D) Linear displacement
Answer: C) Radian measure
Rationale: The radian is defined as the ratio of the arc length (s) to the radius (r): θ
= s/r. When s equals r, the angle is exactly 1 radian. This relationship is
fundamental to understanding angular kinematics and the relationship between
linear and angular motion.
7. Which of the following describes lateral rotation of the hip or shoulder
joint?
• A) Internal rotation
• B) External rotation
• C) Horizontal adduction
• D) Horizontal abduction
Answer: B) External rotation
Rationale: External rotation (also called lateral rotation) involves rotating the limb
outward, away from the midline. At the shoulder, this means the palm faces
