exam 3

a basketball is dropped from a height 3m onto concrete floor. if the coefficient of restitution between the ball and floor is 0.8, how high will the ball bounce?

(0.8^2)x3 = 1.92 m

if a 120kg basketball player travelling 9m/2 to the right collides head-on with a 75kg player travelling 8m/s to the left calculate the momentum of the first player

(120)x(9) = 1080 kg . m/s

calculate kinetic energy of a 500kg roller coaster car that is moving 15 m/s

(15^2x500)x0.5 = 56250 J

a javelin thrower orients himself perpendicular to the wind direction. given that the javelin travels through the air with a horizontal velocity of 20 m/s and the velocity of the wind is 3 m/s how to calculate the resultant velocity of the javelin

(20x20)+(3X3)=409, sqrt409= 20.22 20.22 m/s

a swimmer orients herself perpendicular to the parallel banks of a river. given that the swimmer's resultant velocity is 5 m/s an the velocity of the current is 2 m/s, calculate how far the swimmer will actually have to swim to get to the other side of the banks of the river 16 m apart

(5x5)+(2x2)=29, sqrt29=5.38, arccos(5/5.38) 16/cos(arccos5/5.38) 17.46 m

one arm in a goniometer is fixed in a way that it extends from the protractor at an angle of ____

0 degrees

a table tennis paddle is gripped with a radius of 0.15 m and has a moment of inertia of 0.00225 kg.m^2. what is the mass of the paddle

0.00225/0.15^2 = 0.1 kg

Lisa, an athlete, participates in a 400-meter sprint. if her velocity at 300 m is 5 m/s, apply an equation of constant acceleration and calculate the acceleration she needs to develop to complete the race in the next 15 seconds

0.22 m/s^2

a system has an angular impulse of 4.8 kg.m^2/s. what is its initial moment of inertia if its initial angular velocity is 5 rad/s and its final angular momentum is 9.2 kg.m^2/s

0.88 kg.m^2

a tennis ball attached to a string attains an angular velocity of 4.5 rad/s in 5 s. determine its angular acceleration

0.9 rad/s^2

Provide 2 examples in sport or rehab where instantaneous velocity is more important than average velocity and 2 examples where average velocity is more important. Provide rationale.

2 examples of where instantaneous velocity is more important than the average velocity are when throwing a discus and doing a high jump. In these instances, the instantaneous velocity is more important because the velocity right before throwing or jumping is going to greatly affect the distance or height in which the body moves. 2 examples of where average velocity is more important than instantaneous velocity are during a 10k run or a timed mile. Average velocity is more important here because the speed and it takes to complete the race is going to be fairly consistent and we want to focus on improving the overall duration of the run.

the magnitude of the vertical component of the ground reaction force during running on a level surface is _____ times the runners body weight

2-3 times

if a 120kg basketball player travelling 9m/2 collides head-on with a 75kg player travelling 8m/s. if the 2 players entangle and continue travelling together as a unit, what is their combined velocity?

2.46 m/s

a system has an angular impulse of 6 kg.m^2/s. what is its final angular velocity if its final moment of inertia is 2.5 kg.m^2 and its angular momentum is 1.5 kg.m^2/s

3 rad/s

bruno kicks a soccer ball with an initial velocity of 5 m/s. he imparts a constant acceleration of 2 m/s^2 to it. if the ball has a velocity of 12 m/s before reaching his teammates, calculate the time it takes for the soccer ball to travel from bruno to his teammate

3.5 s

an object is being accelerated at 20 rad/s^2. given a radius of rotation of 1.5m, determine the tangential acceleration of the object

30 m/s^2

richard lifts a 30kg boulder and places it at an elevation of 2 m. the boulders potential energy is _____

30x9.81x2 = 588.6 J

what is the torque generated if a force of 12 N is applied at a perpendicular distance of 3 m from an axis of rotation

36 N-m

what is the mechanical advantage of a lever whose resistance arm is 6.6m and force arm is 4.4 m

4.4/6.6= 0.667

using Newton's second law of motion, calculate the resulting acceleration if a 10 kg ball is struck with a force of 50N

5 m/s^2

the mass of a body is 6 kg, its angular velocity is 10 rad/s, and its radius of gyration is 4m. what is its angular momentum

6x4^2x10 = 960 kg.m^2/s

alisha an athlete completes a 10 km race in 75 minutes, calculate her average velocity

8 km/hr

a ball is hit by a racket at point A, which lies 40cm from the racket's axis of rotation. if the angular velocity of the racket was 20 rad/s at the instant that the ball was contacted, what was the linear velocity at point A?

8 m/s

the angle at the elbow at which flexion torque is produced is approximately ______, with torque capability progressively diminishing as the angle at the elbow changes in either direction

80 degrees

cat rotation is accomplished most effectively when the 2 body segments are in a _____ pike position

90 degree

23. 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

A. It is greater with respect to the wrist than with respect to the elbow.

15. 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

A. Newton's first law of inertia

32. According to Newton's 2nd Law, what is the relationship among torque, moment of inertia, and angular acceleration? A. T = Iα B. I = Tα C. α = TI D. T = Iω

A. T = Iα

30. 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

A. compensatory rotation in lower body in opposite direction

10. Somersaulting occurs around which of the following axes of rotation? A. frontal B. sagittal C. longitudinal D. all of the above

A. frontal

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

A. increase

28. What are the appropriate units for angular momentum? A. kg•m2/s B. kg•m/s2 C. kg2•m/s D. kg•m2

A. kg•m2/s

22. 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

A. massive thighs and slimmer lower legs

16. 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

A. radial acceleration

38. 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

A. reduces moment of inertia of the leg with respect to the hip

37. 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

A. tangent to the circular path at release

34. 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

A. tangential linear velocity

newtons second law expressed algebraically in angular terms

T = Ialpha

Tt = deltaH = (Iw)2 - (Iw)1, formula for angular impulse, each symbol means what T t H I w subscript 2 subscript 1

T=torque, t=time, H=angular momentum, I= moment of inertia, w=angular velocity, subscript 2= final point in time, subscript 1=initial point in time

39. 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

A. k is reduced

13. 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

B. angular velocity

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

B. further from the axis

20. 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

B. inertia

40. 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

B. to increase the moment of inertia of the club head rotating around the shaft

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

B. Angular Velocity

Torque is the angular analogue of what? A. momentum B. force C. mass D. impulse

B. Force

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

B. Increased

Moment of inertia is the angular analogue of what? A. moment of force B. moment of time C. mass D. surface area

C. mass

_____ refers to the concept indicating a balance between applied forces and inertial forces for a body in motion

D'Alembert's principle

12. 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

D. angular momentum

21. 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

D. both A and B

26. Which of the following is/are accurate formula(s) for angular momentum? A. H = Iω B. H = mk2ω C. M = mv D. both A and B E. all of the above

D. both A and B

31. 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

D. both A and B

35. 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

D. both A and B

17. Which of the following is known as "center-seeking" force? A. momentum B. acceleration C. centrifugal force D. centripetal force

D. centripetal force

5. 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

D. m and k

11. Which of the following variables affects angular momentum? A. linear velocity B. angular acceleration C. both A and B D. neither A nor B

D. neither A nor B

what formulas can be used to calculate centripetal force (Fc)

Fc = mv^2 / r Fc = mrw^2

Provide 2 examples in sport, dance or rehabilitation where maximum stability is desired and explain various ways this can be accomplished.

Football linemen are an example in sport when maximum stability is desired. This is because they are expected to maintain their positions despite the forces exerted on them by the opposing linemen. When these athletes are more massive it is advantageous because then more force is required to produce an acceleration or to push the linemen over. A second example is when batting. Hitting will improve if the grip between the hands and the bat is at maximal stability. Batting gloves help to increase the amount of friction between the hands and the bat which means more force is required to initiate motion. Therefore, the grip will stay in tact while batting.

what formula is used to calculate angular momentum

H = mk^2w

what formula is used to calculate the moment of inertia for a body of known mass such as segments of the human body or the body as a whole in different positions

I = mk^2

formula for moment of inertia for a single particle

I = mr^2

unit of friction

Newton

Explain why pulling a heavy object is easier than pushing it, including appropriate formulas in your answer.

When pushing, the force is directed downwards, whereas when pulling, the force is directed upwards. So, from a mechanical perspective, it is easier to pull than to push an object because pulling decreases the magnitude of reaction force and force of max friction, but pushing increases the two. When the reaction force is decreased, friction is decreased so it becomes easier to initiate motion. Fm = (greek u)sR

boat race, 2 crew members push boat to get it moving, average force 130 N in direction of motion of 120kg boat for 5 seconds what is the boats speed neglecting friction?

[(130)(5)]/120 = 5.42 m/s

a 600N person runs up a flight of 50 stairs 42 cm high during a 25-s period. how much mechanical power?

[(50x0.42)x600]/25 = 504 watts

The amount of torque which must by generated by the biceps brachii at the elbow in order to maintain the arm in a particular position is 50 Nm. If the biceps attaches to the radius at a perpendicular distance of 3 cm from the joint center at the elbow, how much force must the muscle produce? a. 1667 N b. 17 N c. 150 N d. 1.5 N

a.

The component of angular acceleration defined as the change in linear velocity for a body traveling on a curved path is what? a. tangential acceleration b. radial acceleration c. angular acceleration d. linear acceleration

a.

The component of angular acceleration directed toward the center of curvature defines what? a. radial acceleration b. tangential acceleration c. angular acceleration d. linear acceleration

a.

When net muscle torque and joint movement occur in the same direction, what type of contraction occurs? a. concentric b. eccentric c. isometric d. isotonic

a.

When the elbow is extended and the elbow flexors contract, which of the component forces acts in addition to the rotary component? a. the stabilizing component of muscle force b. the dislocating component of muscle force c. both the stabilizing component of muscle force and the dislocating component of muscle force d. none of these answers is correct

a.

When two bodies collide head-on and then continue to travel collectively in the original direction of motion of one of the bodies, what factor determines the direction of collective motion after the collision? a. the relative moments of the two bodies b. the relative masses of the two bodies c. the relative acceleration of the two bodies d. the relative weights of the two bodies

a.

Which of the following are scalar quantities? a. angular distance b. angular velocity c. both angular distance and angular velocity d. neither angular distance nor angular velocity

a.

Which of the following components of projectile is affected by gravity? a. vertical component b. horizontal component c. both vertical component and horizontal component d. depends on the individual situation

a.

Which of the following is a correct unit of mechanical energy? a. joules b. watts c. kg-m d. kg/m

a.

Which of the following relationships is correct? a. m = F / a b. F = m / a c. a = m / F d. none of these answers is correct

a.

the relationship between impulse and momentum is derived from Newtons law of _________

acceleration

much human movement involves simultaneous tension development in _______ muscle groups, the latter of which controls the velocity of the movement and enhances the stability of the joint at which the movement is occuring

agonist and antagonist

what results in an increase in radial acceleration

an increase in linear velocity

a(n) ______ is composed of 2 sides that intersect at a vertex

angle

angular velocity increases in the positive direction or decreases in the negative direction when ________

angular acceleration is positive

the difference in the initial and final positions of a moving body is assessed by _______

angular displacement

_____ is measured as the sum of all angular changes undergone by a rotating body

angular distance

the linear displacement (s) is expressed as r(phi), where r is the radius of rotation and phi represents the _______

angular distance

change in angular momentum equal to the product of torque and time interval over which the torque acts is known as ________ _________

angular impulse

what is the formula Isws + mr^2wg used to calculate or an airborne somersault

angular momentum for a single segment

in a relationship v=r(omega), if v represents the tangential velocity of a point of interest and r represents the radius of rotation of that point, what does omega represent

angular velocity

the angular acceleration is expressed as delta-omega/delta-t, where delta-t represents the change in time and delta-omega represents the change in ________

angular velocity

the rate of change in the angular position or orientation of a line segment in a given time period is known as ________ ________

angular velocity

the highest point in the trajectory of a projectile is known as the ______

apex

when a weight vector is drawn for an object displayed in a free body diagram, it acts _______

at the center of gravity

the center of gravity of a perfectly symmetrical object of homogenous density is _______

at the exact center of the object

____ is measured after an athlete completes a marathon

average velocity

in the formula for determining the resistance of a particle to angular acceleration, the radius of rotation of a particle changes as the _________ changes

axis of rotation

If acceleration is constant and positive, velocity is what? a. zero b. increasing c. decreasing d. need more information

b.

If angular acceleration is constant, then angular velocity must be a. constant. b. increasing or decreasing. c. equal to zero. d. none of these answers is correct.

b.

If the knee joint goes through 100° of flexion during the down phase of a squat, what is the total angular distance during 10 complete squats? a. 1000° b. 2000° c. 0° d. none of these answers is correct

b.

If the velocity of a sailboat changes from 4 m/s to 2 m/s over a period of time, what is true of the sailboat's acceleration? a. it is positive b. it is negative c. it is equal to zero d. it is equal to 2 knots/hr

b.

Negative mechanical work involves which of the following? a. net torque and angular motion are same direction b. net torque and angular motion are in different directions c. concentric muscle contraction d. none of these answers is correct

b.

The ability to control equilibrium defines what? a. stability b. balance c. mobility d. center of mass

b.

What does the letter "r" stand for in the equation v = rω? a. resultant b. radius of rotation c. radian d. none of these answers is correct

b.

Which angular direction is conventionally regarded as positive? a. clockwise b. counterclockwise c. flexion d. extension

b.

Which of the following correctly describes impact? a. large force applied over a long period of time b. large force applied over a short period of time c. small force applied over a long period of time d. small force applied over a short period of time

b.

Which of the following factors does not affect the amount of friction generated between two dry surfaces? a. the coefficient of friction between the two surfaces b. the surface area in contact c. the reaction force d. the normal force

b.

Which of the following is a correct unit of mechanical power? a. joules b. watts c. kg-m d. kg/m

b.

the angular orientation of a body segment with respect to a fixed line is known as ______ _______ __________

body segment orientation

factors that effect torque of joints during movement

body weight, movement speed, kinematics of a movement

A runner completes 1 full lap around a 400 meter track. What is her displacement? a. 400 meters b. 400 meters × 2π c. zero d. need more information

c.

Radial acceleration is directly affected by which of the following? a. tangential velocity b. radius of rotation c. both tangential velocity and radius of rotation d. none of these answers is correct

c.

What determines the time a horizontally projected object remains in the air? a. weight b. mass c. projection height d. all of these answers are correct

c.

What quantity is calculated as the inverse of speed? a. velocity b. acceleration c. pace d. none of these answers is correct

c.

What variable may be described as "the quantity of motion" possessed by an object? a. force b. inertia c. momentum d. velocity

c.

When a long jump performance is analyzed, which of the following is likely to be of the most interest? a. the average velocity of the jumper during the run-up b. the instantaneous velocity of the jumper at takeoffCorrect c. the average velocity of the jumper during the flight d. the instantaneous velocity of the jumper at landing

c.

Which of the following affects the time that a horizontally projected object remains in the air? a. weight b. mass c. projection height d. all of these answers are correct

c.

Which of the following affects the time that a horizontally projected object remains in the air? a. weight of projectile b. mass of projectile c. projection height d. all of these answers are correct

c.

Which of the following factors typically exerts the most influence on the horizontal displacement obtained by a projectile? a. projection angle b. relative height of projection c. initial speed of projection d. initial acceleration of projection

c.

Which of the following is/are function(s) of antagonist muscles? a. control velocity of movement b. enhance stability of the joint c. both control velocity of movement and enhance stability of the joint d. none of these answers is correct

c.

Which of the following statements is true of the amount of horizontal force required to start an object sitting on a horizontal surface in motion? a. it must be greater than the coefficient of kinetic friction b. it must be greater than the coefficient of static friction c. it must be greater than the maximum static friction force d. it must be greater than the maximum kinetic friction force

c.

which is an instance of conservation of angular momentum a. diver transitions from standing on springboard to jumping off one b. acrobat is swung across a gap and is pushed midair into a pool c. diver transitions from a somersault rotation to a twisting one midair

c.

radial acceleration is always directed toward the ________

center of curvature

the force that prevents a rotating body from leaving its circular path while rotation occurs around a fixed axis is known as _______

centripetal force

the _______ is a number that serves as an index of the interaction between 2 surfaces in contact

coefficient of friction

the _____ describes the relative elasticity of an impact

coefficient of restitution

a pair of equal and opposite force is known as a force _____

couple

because air resistance is disregarded in discussing and solving problems related to projectile motion, it allows _____ a. treating vertical component as a variable quantity b. treating vertical component as an unchanging quantity c. treating horizontal component as a variable quantity d. treating horizontal component as an unchanging quantity

d

in which example is the distance covered by a moving body the same as its magnitude of displacement a. during 5km race b. during an Indy Car racing competition c. when a swimmer swims across a lake during a triathlon d. when a skier traces a rectilinear path when travelling down a slope

d

A 500 N gymnast performing a giant swing with an angular velocity of 5 rad/sec, exerts 90 Nm of torque on the support bar. How much torque is exerted by the bar on the gymnast's hands? a. 100 Nm b. 2500 Nm c. 590 Nm d. 90 Nm

d.

New blade designs have resulted in extremely low values for the kinetic friction coefficients of ice hockey skates on ice. a. N•m b. N•m/s c. kg•m d. kg•m/s

d.

Once a projectile is airborne, it is affected by which of the following? a. gravity b. air resistance c. release velocity d. both gravity and air resistance e. all of these answers are correct

d.

The ability of a muscle to generate torque is affected by which of the following? a. length of the moment arm b. angle of insertion of the muscle c. cross-sectional area of the muscle d. all of these answers are correct

d.

Which of the following affects the force-generating capability of a muscle? a. the muscle length and cross-sectional area b. the angle and distance from the joint center of the tendon c. attachment to bone the velocity of muscle shortening d. all of these answers are correct

d.

Which of the following is a characteristic of torque? a. it is a vector quantity b. it is characterized by magnitude c. it is characterized by direction d. all of these answers are correct

d.

Which of the following is/are scalar quantity(ies)? a. distance b. speed c. displacement d. both distance and speed

d.

Which of the following must be true for an object to be in a state of static equilibrium? a. the sum of all vertical forces acting on the object must be equal to zero b. the sum of all horizontal forces acting on the object must be equal to zero c. the sum of all torques acting on the object must be equal to zero d. all of these answers are correct

d.

Which type of equipment provides constant velocity? a. Isotonic b. Free weights c. Nautilus d. Isokinetic

d.

3 equation that represent the laws of constant acceleration

d=v1t+1/2at^2 v2=v1+at v2^2=v1^2+2ad

identify the measures of angular displacement and angular distance

degree, radian, revolution

units of angular acceleration

degrees/s^2 revolutions/s^2 radians/s^2

formula relating linear and angular displacement

delta-s = r-delta-phi

_____ component pulls a bone away from a joint center

dislocating

when the line of action of a body's weight moves outside the base of support, a torque is created that tends to cause angular motion of the body, thereby ________

disrupting stability

factors that influence the magnitude of angular momentum of a body

distribution of the body's mass with respect to the axis of rotation, mass of the body, angular velocity of the body

Which one of the following incorrectly identifies the parts of a lever within the human body? a. a bone is the rigid bar b. a joint is the axis of rotation c. a muscle insertion provides the point of force d. COM of the moving segment is the point of resistance e. all of these answers are correct

e.

Which statement is true regarding moment arm? a. Moment arm is largest when the angle of pull on a bone is 90°. b. Changes in moment arm directly affect joint muscle torque. c. For torque to remain constant, more force must be produced when moment arm decreases. d. Both moment arm is largest when the angle of pull on a bone is 90° and changes in moment arm directly affect joint muscle torque. e. All of these answers are correct.

e.

when an airborne volleyball player with a total-body angular momentum of zero performs a spike, moving the hitting arm with a higher angular velocity and a large angular momentum, there is a compensatory rotation of the lower body, producing a(n) ___________

equal amount of angular momentum in the opposite direction

a state characterized by balanced forces and torques is known as ________

equilibrium

Harder running surfaces result in greater ground reaction forces.T/F

false

T/F In anatomical reference position, all joint angles are positioned at 90 degrees

false

T/F by definition, the weights positioned on opposite sides of the center of gravity of a body are always equal

false

T/F in the relationship at=r(alpha), angular acceleration must be expressed in length-based units for the relationship to be accurate

false

T/F kinetic friction force varies with the amount of applied force or the speed of the occurring motion

false

T/F with reference to the purposes served by a lever system, whenever the moment arm of force applied on a lever is greater than the moment arm of resistance, the magnitude of the applied force needed to move a given resistance is more than the magnitude of the resistance

false

Newton's _____ law explains in angular analogue that a rotating body will maintain a state of constant rotational motion unless acted on by an external torque

first

a lever positioned with the applied force and the resistance on opposite sides of the axis of rotation is known as a _____

first-class lever

if the tangential linear velocity is doubled, the radial acceleration increases by a factor of ______

four

a force acting at the surface in contact in the direction opposite the direction of motion or impending motion is referred to as ______

friction

the point of support, or axis, about which a lever may be made to rotate is known as a _____

fulcrum

when the mechanical advantage is __________ than one, the magnitude of the applied force required to move the resistance of a lever is less than the magnitude of the resistance

greater

high jumpers, long jumpers, and pole vaulters lower their centers of gravity prior to takeoff, which enables them to lengthen the vertical path over which their bodies are accelerated during takeoff, thus facilitating a(n) _______

high vertical velocity at takeoff

a discus is releases with an initial speed of 4 m/s at an angle of 60 degrees to the horizontal. what are horizontal and vertical components

hori- 2 m/s vert- 3.46 m/s

a shot put is released with an initial speed of 5 m/s at an angle of 30 degrees. what is horizontal component, what is vertical component

hori- 4.33 m/s vert- 2.5 m/s

_____ is a component of projectile motion that relates to the distance a projectile travels

horizontal component

horizontally positioning the center of gravity of a body near the edge of its base of support on the side of an oncoming external force _______

increases the body's ability to maintain equilibrium

what are factors that increase the resistance of a body to angular acceleration

increasing body's mass, positioning the body's mass away from the axis of rotation

a piece of weightlifting equipment will remain in a fixed position unless lifted, pushed, or pulled by a person exerting a net force on it. this is implied by the law of ___________

inertia

the _____ ______ of a projectile is a vector quantity incorporating both the angle and the initial speed of projection into a single quantity

initial velocity

the center of rotation at a given joint angle, or at a given instant in time during a dynamic movement, is called _________

instant center

______ is measured at the moment of release of a javelin thrower

instantaneous velocity

the variables k and x in the formula for strain energy are interpreted as _____ and _____

k= spring constant x= distance over which the material is deformed

____ describes the appearance of motion

kinematics

the friction force present during motion is referred to as _____ _______

kinetic friction

_____ describes the forces associated with motion

kinetics

what factors influence ground reaction force patterns

knee flexion angle at contact, light intensity, stride length footwear

newton's _____ states that all bodies are attracted to one another with a force proportional to the product of their masses and inversely proportional to the square of the distance between them

law of gravitation

newtons third law of motion is the _______ which states that for every action, there is an equal and opposite reaction

law of reaction

during sprinting, maximum angular acceleration of the ________ is desired

leg

when projection angle and other factors are constant for a projectile, the projection speed determines the _____ of a projectile's trajectory

length

the instantaneous or the average values of angular speed, velocity, and acceleration are dependent on the ________

length of the time interval selected

when the mechanical advantage is ________ than one, the magnitude of the applied force required to move the resistance of a lever is greater than the magnitude of the resistance

less

____ is defined as the rate of change in velocity, or the change in velocity occurring over a given time interval

linear acceleration

tangential acceleration represents the change in ____

linear speed for a body travelling on a curved path

______ is the change in displacement that occurs during a given period of time

linear velocity

when projection velocity is constant, greater relative projection height translates to _____

longer flight time and greater horizontal displacement of the projectile

cat rotation is performed around the _____ axes or the 2 major body segments because it is easier to initiate rotation around these axes

longitudinal

a common unit of acceleration in the metric system is _____

m/s^2

the ____ of a torque created by a given force is equal to Fd

magnitude

the _____ of a torque created by a given force is equal to Fd

magnitude

what is the formula for angular impulse

Tt, where t is torque and t is time

principle of work and energy is represented as _____

W = KE + PE + TE

the moment of inertia of an entire body is the sum of the moments of inertia of all the ____________ the body contains

mass particles

in the segmental method of determining a person's center of gravity location, ______ have a larger influence on total-body center of gravity than many other factors

massive body segments

when the magnitude of force applied on a stationary body becomes greater and greater, the magnitude of the opposing friction also increases to a certain critical point. at that point, the friction force present is termed ________

maximum static friction

a true statement about the metric system is that it is based on the most common international unit of length, the ______

meter

within the human body, the _____ for a muscle with respect to a joint center is the perpendicular distance between the muscle's line of action and the joint center

moment arm

3 names for the shortest perpendicular distance between a force's line of action and the axis of rotation

moment arm force arm lever arm

____ may be defined as the quantity of motion that an object possesses

momentum

the larger the impulse generated, the greater the change in a performer's ______

momentum

when an impulse acts on a system, the result is a change in the system's total ________

momentum

_______ is force acting perpendicular to 2 surfaces in contact

normal reaction force

factors that govern the magnitude of force of max static friction or kinetic friction

normal reaction force, coefficient of friction

the law of acceleration states that a force applied to a body causes an acceleration of that body of a magnitude proportional to the force, in the direction ____________

of the force, and inversely proportional to the body's mass

a _____ _______ impact is an impact during which the relative velocities of 2 bodies are the same as their relative velocities before the impact

perfectly elastic

a ____ ________ impact is an impact during which one of the bodies in contact deforms and does not regain its OG shape

perfectly plastic

counterclockwise is _________ and clockwise is ________

positive negative

in mechanics, ______ refers to the amount of mechanical work performed in a given time

power

a body in free fall that is subject only to the forces of gravity and air resistance is called a ______

projectile

the distribution of a body's mass with respect to the axis of rotation (r) is more important than the total amount of body mass (m) in determining resistance to angular acceleration because ____________

r is always squared

tehe rate of change in direction of a body in an angular motion is called the ______

radial acceleration

identify a unit that serves as a conversion factor between linear and angular measurements

radian

if v represents the tangential velocity of a point of interest, r represents the radius of rotation of that point, and omega represents the angular velocity of the rotating body, the relationship v=r(omega) is valid if omega is expressed in ________

radian-based units

in the context of angular measured used in biomechanical analyses, _____ are often quantified in multiples of pi

radians

radial acceleration increases when ________

radius of curvature decreases

in the formula for moment of inertia (I=mk^2) what does k represent

radius of gyration

the distance from an axis of rotation to a point at which the mass of a body can theoretically be concentrated without altering the inertial characteristics of the rotating body is known as the _________ __________ _________

radius of gyration

what should be quantified in the same units of length to satisfy the relationships s=r(phi), where s is the linear distance, r is the angular distance, and phi is the radius of rotation

radius of rotation and linear distance

the arrangement of most third-class muscle-bone lever systems in the human body promotes _________

range of motion and angular speed of the body segments

the mechanical effectiveness of a lever for moving a resistance may be expressed quantitatively as the ________

ratio of the moment arm of the force to the moment arm of the resistance

a specifically constructed board for determining the center of gravity location of a body positioned on top of it is known as a(n) ____________ _________

reaction board

a goniometer is used to measure the _______

relative joint angles on a live human subject

the difference between projection height and landing height of a projectile is known as its ____ ______ ______

relative projection height

the principle of conservation of momentum states that in the absence of external forced, the total momentum of a given system ________

remains constant

according to the principle of conservation of angular momentum, in a one and a half front somersault dive, a diver leaves the springboard with a fixed amount of angular momentum that _________

remains constant throughout the dive

in the case of an impact between a moving body and a stationary one, the velocity of the stationary body ________

remains zero

one _________ transcribes an arc equal to a circle

revolution

what are units of angular speed and angular velocity

revolutions/min degrees/sec radians/sec revolutions/sec

the procedure for identifying the direction of an angular motion vector is known as the ____ _______ ________

right hand rule

in the context of friction, ____occurs because both curved and flat surfaces are slightly deformed during contact

rolling friction

identify the 3 mechanical factors that affect the trajectory of a projectile

the relative height of projection, the angle of projection, the projection speed

2 factors that influence the value of the coefficient of friction

the relative roughness and hardness of surfaces in contact and the type of molecular interaction between surfaces

with reference to the purposes served by lever systems, whenever the resistance arm of the lever is longer than the force arm, ________

the resistance may be moved through relatively large distance

what are the characteristics of the segments of the human body that make it difficult to determine exact moment-of-inertia values for individual segments and for the body as a whole in different positions?

the segments are irregular shapes, the segments have heterogeneous mass distributions

what is the principle of conservation for angular motion

the total angular momentum of a given system remains constant in the absence of external torques

Newton's __________ law explains in angular analogue that for every torque exerted by one body on another, there is an equal and opposite torque exerted by the seconds body on the first

third

a lever positioned with the applied force between the fulcrum and the resistance is known as a _________

third-class lever

the product of a force and the perpendicular distance from the force's line of action to the axis of rotation is known as _____

torque

the product of a force and the perpendicular distance from the forces line of action to the axis of rotation is known as _____

torque

the rotary effect created by an applied force is known as ______, or moment of force

torque

in the context of projectile trajectory, _____ is solely dependent on the angle of projection

trajectory shape

during the execution of a serve in tennis, expert players not only strike the ball with the arm fully extended but also vigorously rotate the body in the _______ plane

transverse

A motionless body is in a state of static equilibrium. T/F

true

If flexion of a joint is positive in direction when viewed from one side, the same motion will be negative in direction when viewed from the opposite side.T/F

true

New blade designs have resulted in extremely low values for the kinetic friction coefficients of ice hockey skates on ice. T/F

true

T/F the closer the coefficient of restitution is to 1, the more elastic is the impact, and the closer the coefficient is to 0, the more plastic the impact

true

T/F the law of inertia states that a body will maintain a state of rest or constant velocity unless acted on by an external force that changes the state

true

T/F when the human body is the projectile during a jump, high takeoff speed serves to constrain the projection angle that can be achieved

true

T/F whenever the moment arm of the force is longer than the moment arm of the resistance, the mechanical advantage ratio reduces to a number greater than one

true

The most common unit of time is second. T/F

true

toddlers exhibit more kinematic variability than adults during walking.

true

____ is a component of projectile motion that relates to the max height achieved by a projectile

vertical component

a 100kg rugby player collides with a 140kg player. if the first player exerts a force of 630N on the second player, how much force is exerted by the second player?

-630 N

a basketball begins rolling off court with an initial velocity of 5 m/s. If the ball has a constant acceleration of -0.5 m/s^2, how long will the ball take to stop, what is equation

10s a=(V2-V1)/t

what is the torque that must be applied to a system for 4.6 seconds to obtain an angular impulse of 11.5 N.m.s

11.5/4.6 = 2.5 N.m

the linear acceleration of an object is 45 m/s^2. if the given radius of rotation is 2.7m, determine the angular acceleration of the object

16.7 rad/s^2

what factors change angular momentum

the length of the time interval over which a torque acts, and the magnitude and direction of an acting external torque

during an airborne somersault, what are the 2 components of the angular momentum of a single segment with respect to the principal axis of rotation passing through the total body center of gravity

the local term and the remote term

the coefficient of static friction between a sled and the snow is 0.25, with a coefficient of kinetic friction of 0.20. a 20 N girl sits on the 250N sled. how much force directed parallel to the horizontal surface is required to start the sled in motion?

the applied force must be greater than 112.5 N

33. Which of Newton's laws (angular analogues) explains why a batter wears cleats? A. 1st law - moment of inertia B. 2nd law - angular acceleration C. 3rd law - reaction D. none of the above

C. 3rd law - reaction

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

C. angular impulse

27. 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

C. both A and B

29. 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

C. both A and B

18. 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

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

24. Which of the following are accurate units for moment of inertia? A. N•m B. N•m2 C. kg•m2 D. kg•m

C. kg•m2

25. 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

C. longitudinal

19. 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

C. on the tires of the cycle

8. 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

C. remain the same

9. How many principle axes are there for the human body? A. one B. two C. three D. four

C. three

36. Which of the following are accurate units for centripetal force? A. kg•m2/s B. kg•deg2/s C. N D. N-kg•m

C. N

what factor most dramatically influences angular momentum of a body

the distribution of the bodys mass with respect to the axis of rotation

the ______ is the unit of work in the metric system

Joule

law of conservation of mechanical energy

PE + KE = C

Explain the concept of instant center of rotation, including a discussion of why it is important when studying human motion.

The center of rotation at a given joint angle, or at a given instant in time during a dynamic movement is called the instant center. This is important when studying human motion because joint motion is often accompanied by a displacement of one bone with respect to the articulating bone at the joint. This makes finding the location of the exact center of rotation difficult because it changes as joint angle changes. The concept of the instant center of rotation can provide an exact location through measurements so that joint angles can be studied.

the rate of gravitational acceleration at which a body is attracted toward the surface of the earth (-9.81 m/s^2) is based on ______

the earth's mass and the distance to the center of the earth

______ influences the vertical, but not the horizontal, component of the projectile motion of a body in free fall

the force of gravity

____ component causes a bone to rotate around a joint center

rotary

angular speed is a ______ quantity

scalar

distance is a _____ quantity and linear displacement is a _____ quantity

scalar vector

Newton's _______ law explains in angular analogue that a net torque produces angular acceleration of a body that is directly proportional to the magnitude of the torque, in the same direction as the torque, and inversely proportional to the body's moment of inertia

second

in a ______, the applied force and the resistance are on the same side of the axis, with the resistance closer to the axis

second-class lever

factors that influence the magnitude of rolling friction

size of the radius of curvature of a rolling body, coefficient of friction between surfaces in contact, the normal reaction force

for any 2 bodies in contact, uk is always _____ than us

smaller

smaller gymnasts have ______, which give them an advantage in performing skills involving whole-body rotations, despite the fact that larger gymnasts may have greater strength and be able to generate more power

smaller moments of inertia

____ is defined as the distance covered divided by the time taken to cover it

speed

units of ____ are units of length divided by units of time

speed and velocity

a golf club has a mass of 0.15kg and a moment of inetia of 0.096 kg.m^2. what is the radius of gyration

sqrt(0.096/0.15) = 0.8 m

a 0.5 kg stone if swung on a 0.7 m string generating a centripetal force of 17.15N. what is the angular velocity of the stone

sqrt(17.15 / 0.5 / 0.7) = 7 rad/s

________ is defined mechanically as resistance to both linear and angular acceleration

stability

________component pulls a bone toward a joint center

stabilizing

____ is the capacity to do work by virtue of a deformed body's return to its OG shape

strain energy

in the segmental method, when the products of each bodys segment's center of gravity location and its mass are summed and subsequently divided by the _______, the result is the location of the total-body center of gravity

sum of all segmental masses

what conditions must be met for a body to be in a state of static equilibrium

sum of all torques, horizontal and vertical forces acting on the body must be zero

a line that touches, but does not cross, a curve at a single point is known as a(n) ______

tangent

when the value of angular distance approaches zero, ______ approximates a straight line

tangential linear displacement

what happens to the angular momentum of a body when the angular velocity is partially transferred from one principal axis of rotation to another in the absence of external forces of torque

the angular momentum of the body remains constant

identify the principal axes the human body moves around when it rotates free of support

the anteroposterior axis, longitudinal axis, and transverse axis