Kinematics and Kinetics Recap

Match the following laws of motion with their correct descriptions.

• An object in motion will eventually come to a stop without any external force.

• An object in motion will eventually come to a stop without any external force.

• 1. An object at rest stays at rest, and an object in motion stays in motion unless acted upon by a net external force.

• The force acting on an object is equal to its mass multiplied by its velocity.

• 2. The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.

• For every action, there is a greater action that cancels it out.

• 3. For every action, there is an equal and opposite reaction.

• 1. An object at rest stays at rest, and an object in motion stays in motion unless acted upon by a net external force. 2. The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. 3. For every action, there is an equal and opposite reaction.

How does the formula F = ma relate to biomechanics?

• F = ma is only for mechanical systems.

• F = ma explains how forces affect the motion and acceleration of body segments.

• F = ma describes muscle energy consumption during exercise.

• F = ma is unrelated to human anatomy and movement.

Answer explanation

F = ma relates to biomechanics by illustrating how forces affect the motion and acceleration of body segments, which is crucial for understanding human movement and performance.

Define projectile motion and its key characteristics.

• Projectile motion occurs when an object is thrown into the air, following a parabolic path due to gravity.

• Projectile motion is vertical motion without a horizontal component.

• The characteristic of projectile motion is a straight-line trajectory.

Answer explanation

The correct choice defines projectile motion accurately as it involves an object thrown into the air, following a parabolic path due to gravity, unlike the other options which misrepresent its characteristics.

How is linear momentum defined and what is its formula?

• p = m / v

• p = m * v

• p = m + v

• p = m - v

Answer explanation

Linear momentum is defined as the product of an object's mass and its velocity. The correct formula is p = m * v, where p represents momentum, m is mass, and v is velocity.

What is angular kinetics and why is it important in biomechanics?

• Angular kinetics focuses on linear motion.

• Angular kinetics studies rotational motion and its forces, important for biomechanics.

• It is irrelevant to human movement.

• Angular kinetics applies only to mechanical systems.

Answer explanation

Angular kinetics is crucial in biomechanics as it studies rotational motion and the forces involved, helping to analyze human movement effectively. This understanding is essential for improving performance and preventing injuries.

What is the formula for angular momentum?

• L = r × p or L = r × (mv)

• L = mv^2

• L = p × t

• L = 1/2 Iω

Answer explanation

The correct formula for angular momentum is L = r × p, where r is the position vector and p is the linear momentum (mv). This shows how angular momentum depends on both the distance from the axis of rotation and the momentum of the object.

Grace is confused about linear and angular kinematics in physics.

• Linear kinematics involves straight-line motion, while angular kinematics involves rotational motion.

• Linear kinematics focuses on velocity, while angular kinematics focuses on acceleration.

• Linear kinematics applies to falling objects, while angular kinematics applies to objects on a surface.

• Linear kinematics involves circular motion, while angular kinematics involves straight-line motion.

Answer explanation

The correct choice highlights that linear kinematics deals with straight-line motion, while angular kinematics pertains to rotational motion. This distinction is fundamental in understanding the two types of motion in physics.

How does torque relate to angular acceleration?

• Torque is directly proportional to angular acceleration.

• Torque is inversely proportional to angular acceleration.

• Torque has no effect on angular acceleration.

• Torque is unrelated to angular acceleration.

Answer explanation

Torque is directly proportional to angular acceleration, as described by Newton's second law for rotation: τ = Iα, where τ is torque, I is moment of inertia, and α is angular acceleration.

How can understanding kinematics improve athletic performance?

• Kinematics is relevant for optimizing athletic movements.

• Kinematics focuses on mental aspects of performance.

• Kinematics helps athletes optimize their movements for better performance.

• Understanding kinematics does not help prevent injuries.

Answer explanation

Kinematics analyzes motion, helping athletes refine their techniques and movements. By understanding body mechanics, athletes can enhance their performance, making this choice the most relevant to improving athletic outcomes.