Question 1

Which of the following is referred to as the "quantity of angular motion" possessed by a body?

Accepted Answer

Angular momentum is referred to as the "quantity of angular motion" possessed by a body. It is a measure of the amount of rotation an object has, taking into account its mass, shape, and speed of rotation.

Question 2

The statement "a rotating body will maintain a state of constant angular motion unless acted on by an external torque" refers to which of the following?

Accepted Answer

This statement is an application of Newton's first law of inertia, which states that an object will remain in its current state of motion unless acted upon by an external force or torque.

Question 3

If a diver goes from a full layout position to a tuck position,what will happen to her angular velocity?

Accepted Answer

When a diver goes from a full layout position to a tuck position, their moment of inertia decreases because their mass distribution is closer to the axis of rotation. According to the conservation of angular momentum, if the moment of inertia decreases, the angular velocity must increase to conserve angular momentum.

Question 4

Centripetal force is related to which of the following?

Accepted Answer

Centripetal force is directly related to radial acceleration, as it is the force that causes an object to move in a circular path, pointing towards the center of the circle. Tangential acceleration, on the other hand, relates to changes in the speed of the object moving along the path, not the direction.

Question 5

If a diver goes from a full layout position to a tuck position,what will happen to his momentum?

Accepted Answer

Momentum is conserved when no external forces act on a system. Changing body position from full layout to tuck doesn't change the diver's mass or velocity, so momentum remains the same.

Question 6

Which of the following are accurate units for moment of inertia?

Accepted Answer

Moment of inertia is correctly expressed in units of kg•m^2, which represents the resistance of a body to changes in its rotational motion.

Question 7

What effect does "choking up" on a bat have?

Accepted Answer

Choking up on a bat reduces the moment of inertia, which in turn allows for a faster swing, thereby increasing the angular velocity of the swing. The mass of the bat does not change; only its distribution relative to the hands changes, affecting the swing dynamics.

Question 8

Which of the following is/are accurate formula(s)for angular momentum?

Accepted Answer

Angular momentum (H) can be expressed as H = Iw, where I is the moment of inertia and w is the angular velocity, and also as H = mk²w, where m is mass, k is the radius of gyration, and w is the angular velocity.

Question 9

Which of the following quantities increases as moment of inertia decreases during the airborne phase of a dive?

Accepted Answer

Angular momentum remains constant due to the conservation of angular momentum, but as the moment of inertia decreases, angular velocity increases to maintain the constant angular momentum.

Question 10

Which of the following is known as "center-seeking" force?

Accepted Answer

Centripetal force is known as "center-seeking" force because it is always directed towards the center of the circular path, keeping an object moving in a circular motion.

Question 11

In the absence of external torque,which of the following will increase when moment of inertia decreases?

Accepted Answer

In the absence of external torque, angular momentum (L = Iω, where I is the moment of inertia and ω is the angular velocity) is conserved. If the moment of inertia decreases, the angular velocity must increase to keep the angular momentum constant.

Question 12

Which of the following accurately describes the radius of gyration of the forearm segment?

Accepted Answer

The radius of gyration of the forearm segment is greater with respect to the wrist than with respect to the elbow because it measures how far from the axis of rotation (in this case, the elbow) the mass of the forearm is effectively concentrated. The farther from the pivot point (elbow), the greater the radius of gyration, reflecting the distribution of mass along the forearm.

Question 13

When a cyclist rounds a curve,where does centripetal force act?

Accepted Answer

The centripetal force acts on the tires of the cycle, as this is where the force is applied to change the direction of the cycle's motion, keeping it moving in a curve.

Question 14

Torque is the angular analogue of what?

Accepted Answer

Torque is the rotational equivalent of linear force. It represents how much a force acting on an object causes that object to rotate around an axis.

Question 15

When knee flexion is increased,what happens to the moment of inertia of the leg about the hip?

Accepted Answer

When knee flexion is increased, the mass distribution of the leg changes, bringing more mass closer to the axis of rotation (the hip in this case). This results in a decrease in the moment of inertia of the leg about the hip, as the moment of inertia is directly related to the distribution of mass relative to the axis of rotation.

Question 16

Centrifugal force is a misnomer. What is really happening when you feel a pull to the outside while rounding a curve?

Accepted Answer

When rounding a curve, the sensation of being pulled outward is due to inertia, which is the tendency of an object to resist changes in its state of motion. The actual force acting on the object to keep it moving in a curve is the centripetal force, directed towards the center of the curve.

Question 17

Rotating around which of the following principal axes of rotation has the least moment of inertia (anatomical position)?

Accepted Answer

The longitudinal axis has the least moment of inertia in the anatomical position because it runs head-to-toe through the body's center, around which mass is most evenly distributed, requiring less torque to rotate.

Question 18

Regarding moment of inertia of the leg with respect to the hip,which of the following leg morphologies would favor a sprinter?

Accepted Answer

Massive thighs and slimmer lower legs favor a sprinter because the moment of inertia is lower when the mass is closer to the axis of rotation (in this case, the hip). This configuration allows for faster acceleration and deceleration of the legs, which is advantageous in sprinting.

Question 19

Which of the following variables contribute to moment of inertia?

Accepted Answer

Moment of inertia depends on the mass of the object (m) and the distribution of that mass around the axis of rotation, often represented by a radius or distance (k).

Question 20

Which of the following acts to produce a change in angular momentum?

Accepted Answer

The answer of Which of the following acts to produce...

Quiz 14: Angular Kinetics of Human Movement