Deck 14: Angular Kinetics of Human Movement

Question 1

Where is radius of gyration located in relation to center of gravity (COG)?

A) closer to the axis
B) further from the axis
C) same distance from the axis
D) need more information

Answer 1

further from the axis

Question 2

Centripetal force is related to which of the following?

A) radial acceleration
B) tangential acceleration
C) both A and B
D) none of the above

Answer 2

radial acceleration

Question 3

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

A) angular momentum
B) angular velocity
C) both A and B
D) neither A nor B

Answer 3

angular velocity

Question 4

Which of the following variables affects angular momentum?

A) linear velocity
B) angular acceleration
C) both A and B
D) neither A nor B

Question 5

Torque is the angular analogue of what?

A) momentum
B) force
C) mass
D) impulse

Question 6

Which of the following is true of a baserunner weighing 70 Newtons and a baserunner weighing 50 Newtons?

A) the centripetal force exerted on the heavier baserunner will be greater
B) the heavier baserunner will not be able to run as fast around the bases, due to a greater centripetal force
C) if the baserunners run at the same velocity around the bases, the heavier baserunner will have to lean in more towards the pitcher's mound due to a greater centripetal force
D) all of the above are true

Question 7

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?

A) Newton's first law of inertia
B) Newton's second law of acceleration
C) Newton's third law of action/reaction
D) none of the above

Question 8

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

A) momentum
B) acceleration
C) centrifugal force
D) centripetal force

Question 9

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

A) on the cyclist's center of gravity
B) on the cycle's center of gravity
C) on the tires of the cycle
D) on the ground

Question 10

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

A) angular momentum
B) angular velocity
C) both A & B
D) none of the above

Question 11

Moment of inertia is the angular analogue of what?

A) moment of force
B) moment of time
C) mass
D) surface area

Question 12

Which of the following variables contribute to moment of inertia?

A) F and d
B) T and t
C) M and v
D) m and k

Question 13

Somersaulting occurs around which of the following axes of rotation?

A) frontal
B) sagittal
C) longitudinal
D) all of the above

Question 14

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

A) moment of inertia
B) torque
C) angular impulse
D) none of the above

Question 15

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

A) centripetal force
B) inertia
C) both A and B
D) none of the above

Question 16

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

A) angular displacement
B) angular velocity
C) angular acceleration
D) angular momentum

Question 17

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

A) increase
B) decrease
C) remain the same
D) need more information

Question 18

How many principle axes are there for the human body?

A) one
B) two
C) three
D) four

Question 19

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

A) increased
B) decreased
C) remains the same
D) need more information

Question 20

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

A) increase
B) decrease
C) remain the same
D) need more information

Question 21

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

A) H = Iw
B) H = mk²w
C) M = mv
D) both A and B
E) all of the above

Question 22

If a pendulum stops swinging, which of the following is/are true?

A) angular velocity = 0
B) angular momentum = 0
C) both A and B
D) none of the above

Question 23

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

A) N·m
B) N·m²
C) kg·m²
D) kg·m

Question 24

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

A) reduces moment of inertia
B) increases angular velocity of swing
C) reduces mass
D) both A and B
E) all of the above

Question 25

Why is a bat easier to swing if you grip the barrel instead of the handle?

A) k is reduced
B) k is increased
C) moment of inertia is increased
D) easier to grip the barrel

Question 26

According to Newton's 2^nd Law, what is the relationship among torque, moment of inertia, and angular acceleration?

A) T = Ia
B) I = Ta
C) a = TI
D) T = Iw

Question 27

Why does a figure skater cross his arms tightly across the chest when performing a quadruple axel?

A) to reduce moment of inertia
B) to increase angular velocity
C) to increase time in the air
D) both A and B
E) all of the above

Question 28

Why are golf club heads weighted?

A) to increase the moment of inertia of the club with respect to the shoulder
B) to increase the moment of inertia of the club head rotating around the shaft
C) to decrease the moment of inertia of the club with respect to the shoulder
D) to decrease the moment of inertia of the club head rotating around the shaft

Question 29

Why do sprint coaches stress "heel to buttocks" during sprinting?

A) reduces moment of inertia of the leg with respect to the hip
B) reduces moment of inertia of the lower leg with respect to the knee
C) reduces moment of inertia of the foot with respect to the ankle
D) there is no scientific basis for this coaching cue

Question 30

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

A) It is greater with respect to the wrist than with respect to the elbow.
B) It is greater with respect to the elbow than with respect to the wrist.
C) It is equal with respect to the wrist and with respect to the elbow.
D) need more information

Question 31

How can a cyclist maintain balance when rounding a sharp curve?

A) slow down
B) lean to the inside of the curve
C) lean to the outside of the curve
D) both A and B
E) none of the above will affect balance

Question 32

If total body angular momentum is 0, what will happen as the result of a forceful movement such as a spike?

A) compensatory rotation in lower body in opposite direction
B) compensatory rotation in upper body called follow-through
C) angular momentum is no longer 0
D) all of the above

Question 33

How come gravity does not affect angular momentum?

A) d_┴ = 0
B) T = 0
C) both A and B
D) gravity does affect angular momentum

Question 34

What are the appropriate units for angular momentum?

A) kg·m²/s
B) kg·m/s²
C) kg²·m/s
D) kg·m²

Question 35

Which of the following is/are most important factor(s) affecting the magnitude of centripetal force?

A) tangential linear velocity
B) radius of rotation
C) mass
D) all of the above are equally important

Question 36

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

A) massive thighs and slimmer lower legs
B) massive lower legs and slimmer thighs
C) leg morphology does not matter
D) need more information

Question 37

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

A) transverse (frontal)
B) anteroposterior (sagittal)
C) longitudinal
D) need more information

Question 38

Which of Newton's laws (angular analogues) explains why a batter wears cleats?

A) 1^st law-moment of inertia
B) 2^nd law-angular acceleration
C) 3^rd law-reaction
D) none of the above

Question 39

When a discus thrower spins and then releases the discus, what direction will it travel?

A) tangent to the circular path at release
B) tangent to the circular path at beginning of spin
C) will continue in circular path
D) need more information

Question 40

Which of the following are accurate units for centripetal force?

A) kg·m²/s
B) kg·deg²/s
C) N
D) N-kg·m

Question 41

The angular analogue of Newton's second law can be stated algebraically as T=Iα.

Question 42

An axis that passes through the body's center of gravity is a ___________________ axis.

Question 43

Torque is the product of force and moment arm, or the product of moment of inertia and ___________________ ___________________.

Question 44

The principle moment of inertia of the human body is greatest around the anteroposterior axis.

Question 45

Explain transfer of angular momentum using an example in sport, dance or rehabilitation.

Question 46

During skilled performance of a throw or strike, momentum is generally transferred from the more proximal segments to the more distal segments.

Question 47

The product of moment of inertia and angular velocity is ___________________ ___________________.

Question 48

Explain conservation of angular momentum using an example in sport, dance or rehabilitation, including appropriate formula.

Question 49

Discuss the factors that affect moment of inertia, including examples.

Question 50

What has historically been referred to as centrifugal force, is really just inertia.

Question 51

Angular impulse is the product of ___________________ and ___________________.

Question 52

When a body is rotating, the force directed toward the center of rotation is called ___________________ force.

Question 53

Discuss the advantages and disadvantages of a small body size (including muscle mass) for a gymnast performing full body rotations.

Question 54

If an airborne performer wishes to maximize the number of revolutions she spins, she should extend the limbs as far from the axis of rotation as possible.

Question 55

Explain why the principal moment of inertia is so much larger around the frontal axis than around the longitudinal axis of a human body.