ES 446 Final
False
(T/F) During walking, the magnitude of GRF from ↑est 2 ↓est is vertical, mediolateral, & anteroposterior.
True
(T/F) Except 4 the few ppl who can hyperextend their knees, the knee joint is always flexed & a + relative angle.
True
(T/F) Force is a vector.
False
(T/F) Frictional force depends on the contact area, & the coefficient of friction btwn the 2 objects of interest.
True
(T/F) Grav & friction r examples of external forces.
True
(T/F) Hip joint power is a proportional 2 hip joint moment & the velocity the thigh is rotating.
True
(T/F) Horizontal acceleration of a golf club head is less than its max @ the moment of impact in a golf swing.
True
(T/F) If a 100N force is applied 2 lift an object w/ a mass of 10kg, that object will b accelerated ↑ward.
True
(T/F) If the right knee rotates CCW abt the foot, that's on the ground, angular velocity is +.
True
(T/F) In a golf swing, the club head is near its max horizontal velocity when contacting the ball.
False
(T/F) In the 1st 1/2 of stance, the rearfoot goes from everted 2 inverted in most runners.
True
(T/F) Laminar flow is most likely 2 occur when the object passing thru the fluid is small, has a smooth surface, & is moving slowly.
False
(T/F) Moment of inertia abt an axis always passes thru the COM of a segment.
True
(T/F) Most movement in a triple axel in skating occurs in the transverse plane.
True
(T/F) Once a gymnast leaves the vault, angular momentum stays constant while airborne if air resistance is neglected.
True
(T/F) Only the force component tangential 2 the rim of a wheelchair causes propulsion.
False
(T/F) PE is proportional 2 an object's mass & inversely proportional 2 its height from the ground.
True
(T/F) Person A, who has 1/2 the mass of Person B, will b able 2 cause the same impulse on an object as Person B if she moves w/ twice the velocity of Person B.
False
(T/F) Points 1 & 40cm from the center of a merry- go-round have the same angular & tangential velocities.
False
(T/F) Ppl r more efficient if they ↑ their stride length 10% more than preffed 4 a given running velocity.
True
(T/F) Rads, °s, & revs r appropriate units 4 angular distance & displacement.
True
(T/F) Range of a projectile is max using a projection angle less than 45° if landing height is ↓er than release height.
True
(T/F) Relative angles don't give info on orientation of the bod or segments in space.
False
(T/F) Relative joint angles r always calc as proximal segment angle minus distal segment angle.
False
(T/F) Resistance of a thigh 2 rotate abt its longitudinal axis is greater than its resistance 2 rotate abt a mediolateral axis.
True
(T/F) Rotational KE of the foot is more influenced by the foot's angular velocity than its moment of inertia.
False
(T/F) Running velocity is a product of stride length & stride rate; ↑ing 1 ↑s velocity.
False
(T/F) Stride length & step length r synonyms.
False
(T/F) Tangential & centripetal accelerations r always parallel 2 each other in angular motion.
True
(T/F) Tangential velocity of a point on a lever is a function of the length of the radius & the angular velocity.
True
(T/F) The absolute angle of the trunk when standing ↑right is 90°.
True
(T/F) The amount of E transmitted from u 2 the H2O when swimming is proportional 2 the disturbance of the H2O.
True
(T/F) The area under a velocity by time graph reps the displacement.
True
(T/F) The center of pressure under ur left foot when standing mayb in a location of 0 pressure.
False
(T/F) The direction of the torque vector ∆s the force vector rotates around the axis of rotation.
False
(T/F) The horizontal velocity of a shot put is slowed by grav 9.81 m/s every sec it's in the air.
False
(T/F) The law of cosines allows 1 2 calc segment angles not @ right angles 2 each other.
False
(T/F) The max point on a position by time graph indicates the point where velocity is also max.
False
(T/F) The moment arm 4 muscle force stays constant thru the entire ROM.
False
(T/F) The moment arm is always measured from the point of application of the force 2 the axis of rotation.
False
(T/F) The moment of inertia abt an axis thru the COM is less than the moment of inertia abt any other perpendicular axis running thru any other point on the segment.
True
(T/F) The moment of inertia abt an axis thru the COM is less than the moment of inertia abt any other perpendicular axis running thru any other point on the segment.
False
(T/F) The norm force is always directed vertically.
False
(T/F) The only force making a moment abt the shoulder when an arm is held out 2 the side is the weight of the whole arm.
False
(T/F) The right-hand rule is used 2 determine if a right or left horizontal is used 2 measure segment angles.
False
(T/F) The segment angle btwn the trunk & the arm abducted out 2 the side is 90°.
True
(T/F) The slope of a line tan 2 a velocity by time curve indicates instantaneous acceleration.
False
(T/F) The sum of torques abt the COM of an object always = 0.
True
(T/F) The x & y-axes in a 2D rectangular reference system r always oriented horizontally & vertically.
True
(T/F) Total bod angular momentum can b ↑ed during a dive by forcefully swinging the arms ↓
True
(T/F) Typ, knee flexion angle is greater @ foot contact when running vs walking.
True
(T/F) U performed vertical jumps on a force platform 2 times. The time u made greater vertical impulse was the time u jumped ↑er.
False
(T/F) Using digitization, calcing shoulder abduction & adduction during a jumping jack is a qualitative analysis.
True
(T/F) Vectors can b −ed graphically by taking the opposite of 1 & placing its tail @ the head of the other vector.
True
(T/F) Velocity is a vector.
False
(T/F) W/ a coordinate ref system originating @ the ankle joint, the axes of the coordinate system will always b horizontal & vertical during 4ward movements, like walking.
False
(T/F) When a force vector is resolved n2 its orthogonal components, the magnitude of the resultant vector is always larger than any of the components.
True
(T/F) When bowling, angular velocity of the arm abt the shoulder is 0 if it's swinging @ a constant angular velocity.
True
(T/F) When u r standing still, the sum of all of the external forces acting on ur bod always = 0.
True
(T/F) While u can pull or push an object, ur muscles can technically only pull, or create tensile forces.
False
(T/F) ↑ing an object's stability can b done by ↑ing the height of the COM or ↑ing its mass.
True
(T/F) ↓ing moment of inertia by going from a laid out 2 tucked bod position when doing a backflip allows 1 2 rotate quicker.
True
(T/F) ∆ in velocity is = 2 the area under an acceleration by time curve.
False
(T/F) − acceleration indicates that the direction of motion is away from the origin in the − direction.
False
(T/F) Displacement & distance are scalar quantities.
False
(T/F) During a long jump, only translational motion occurs.
False
(T/F) During running, hip flexion, knee extension, & ankle DF occur during initial ground contact.
False
(T/F) During sprinting, a greater % of the gait cycle is spent in stance relative 2 walking bc ↑er forces need 2 b made.
True
(T/F) During the stance phase of running, + power @ the hip, knee, & ankle joints indicates eccentric contractions.
B
Calc the range of the throw. A. 29.9m B. 42.6m C. 26.1m D. 37.2m
True
(T/F) 2 calc angular velocity when kicking a ball, ur thigh length is the radius of rotation abt the hip.
True
(T/F) 2 pushing & pulling forces acting on the same point @ the same time can b +ed 2gether & repped as 1 resultant force.
False
(T/F) 2 work ur deltoids more during a lateral arm raise, bend ur elbows slightly, bringing the weight closer 2 ur trunk.
False
(T/F) 2nd-class levers need big effort forces relative 2 resistant forces & max the speed of movement.
True
(T/F) 3rd-class levers, where the effort & resisting forces r on the same side of the fulcrum, r most prominent in the bod.
True
(T/F) 4 a force to cause a rotation, it must not pass thru the pivot point.
False
(T/F) 4 cyclical movements, time is plotted on the x-axis & a segment angle is plotted on the y-axis.
True
(T/F) @ faster walking speeds, 1 1st ↑s their step frequency & then stride length.
True
(T/F) A + net moment indicates that angular acceleration is occurring.
True
(T/F) A + value on a velocity by time curve indicates that the corresponding position mayb + or −.
False
(T/F) A 2D ref frame has 2 axes & 2 planes.
False
(T/F) A force couple makes only rotation w/o translation bc the 2 torques act in the same direction.
True
(T/F) A force has 2 b applied over sum time interval 4 an impulse 2 b made.
False
(T/F) A golf swing is best modeled as a single pendulum, w/ the arm, wrist, & club all rotating abt the shoulder.
False
(T/F) A pole vaulter in flight has only KE.
False
(T/F) A radius & a rad r the same thing.
False
(T/F) A shuffleboard puck slows as it slides on the floor. Its ∆ in E is equivalent 2 the ∆ in power.
True
(T/F) Acceleration is def as the time rate of ∆ of velocity.
True
(T/F) An MA > 1 indicates the effort arm exceeds the resistance arm, which magnifies the moment made by the effort force.
True
(T/F) An ankle joint w/ an angular velocity of −2.4rad/s is PFing.
True
(T/F) An object in motion won't stop unless sum external force acts on it.
True
(T/F) An object's mass is a gud estimate of its inertia.
True
(T/F) Angular displacement can only range from 0-2π but angular velocity can range from − 2 + ∞.
True
(T/F) Angular momentum ↑s if moment of inertia ↑s & ↓s when angular velocity ↓s.
True
(T/F) As long as the distance btwn ur COM & the earth's COM is constant, so is grav.
True
(T/F) Assuming ur mass is constant when u sleep, u can ↓ pressure by lying on ur back vs ur side.
False
(T/F) Backspin imparted on a golf ball is an example of the Magnus effect, when ↓ pressure on the bottom & ↑ pressure on the top results in the ball lifting ↑ward.
False
(T/F) CW torques r considered 2 b +.
True
(T/F) Centripetal acceleration is proportional 2 the inverse of the distance of an object from the axis of rotation.
False
(T/F) Choking ↑ on a golf club ↑s the tangential & angular velocities of the club head.
False
(T/F) Cycle frequency ↓s as wheelchair propulsion velocity ↑s.
Tangential Acceleration
The ∆ in linear velocity per unit time of a bod moving along a curved path
Force Couple
2 forces, = in magnitude, acting in opposite directions, that make rotation abt an axis
D
2 marbles have the same size & mass. Marble A is dropped from a height of 9.81m & Marble B is given an initial horizontal velocity of 9.81m/s & vertical velocity of 0m/s. Wat marble will contact the ground first? A. Marble A B. Marble B C. Both marbles will contact @ the same time
Coplanar Forces
2 or more forces acting in the same plane
B
Calc the impulse of a force that ↑s @ a constant rate from 0 2 3N over 3s & then ↓s @ a dif constant rate from 3 2 0N in 4s. A. 27Ns B. 10.5Ns C. 21Ns D. 3Ns
A
@ takeoff, the horizontal & vertical velocities of a ↑ jumper r 2.0 & 3.9m/s. Wat r the resultant velocity & angle of takeoff? A. v = 19.2m/s; θ = 62.9° B. v = 5.9m/s; θ = 27.1° C. v = 4.4m/s; θ = 62.9° D. v = 4.4 m/s; θ = 27.1°
A
A 100N force is applied 2 a box @ an angle of 60° 2 the horizontal via a rope. How much force "lifts" the box & how much "pulls" it along the surface? A. 86.6N; 50N B. 100N; 100N C. 50N; 50N D. 50N; 86.6N
D
A 1300kg car starts 2 roll ↓ a road w/ a 30° incline. Ppl rush 2 stop it. How much force must they apply 2 stop it? A. 1300N B. 11044N C. 12753N D. 6377N
A
A 14000kg truck is traveling @ 20m/s. Wat would b the velocity of a 10000kg truck w/ the same momentum? A. 28m/s B. 20m/s C. 32m/s D. 40m/s
C
A 150kg football player is running 2 another player @ 11.1m/s. How much force needs 2 b applied over 2s 2 bring him 2 a stop? A. 1665N B. 13.5N C. 833N D. Need 2 kno the other player's mass 2 solve.
C
A 4.12N ball needs 2 b accelerating in the vertical direction @ 20 m/s2 2 reach its target height. How much force must b exerted in the vertical direction 2 accomplish this? A. .206N B. 4.85N C. 8.4N D. 4.12N
D
A 55kg gymnast applies a vertical GRF of 1100N @ .17m behind the COM during a 4ward somersault. Assume she's facing the right. Wat's the torque made abt the COM? A. 279N-m B. −92N-m C. 187N-m D. −187N-m
B
A 608N woman dives from a 10m platform. Wat's her PE & KE 7m n2 the dive? a. KE = 1824J; PE = 4255J b. KE = 4255J; PE = 1825J c. KE = 41744J; PE = 17903J d. KE = 17903J; PE = 41744J
A
A baseball leaving the bat @ 46° @ a height of 1.2m from the ground clears a 3m high wall 125m from home plate. Wat's the initial velocity of the ball (ignore air resistance)? A. 34.9m/s B. 35.3m/s C. 35m/s D. 36.9m/s
D
A bike wheel makes 1.5revs w/ an avg angular velocity of 18rad/s. U put ur hand on the wheel 2 slow it @ a rate of 500°/s2. How much angular distance is traveled b4 the wheel cums 2 a stop? A. 1064° B. 2152° C. 9.43rad D. 28rad
B
A bobsled accelerates from rest @ a constant rate of 3m/s2. How fast is it going after 3.5s? A. 6.5m/s B. 7m/s C. 9m/s D. 10.5m/s
Statics
A branch of mechanics that the system being studied does no acceleration
B
A constant force of 160N acts on an object in the horizontal direction. The force moves the object 4ward 75m in 2.3s. Wat's the object's mass? A. 22.6kg B. 5.64kg C. 11.28kg D. 60kg
D
A cyclist avgs 99rpm during a race. Wat was his angular velocity in rad/s? A. 5.18 B. 622 C. 99 D. 10.36
D
A discus thrower rotates thru the last 50° of a turn in .12s. The distance from his shoulder 2 his hand is 1m & the distance from the axis of rotation 2 the center of the discus is 1.17m. Calc the avg linear velocity of the discus. A. 488m/s B. 416m/s C. 7.27m/s D. 8.51m/s
D
A diver accelerates thru a somersault @ 802°/s. Wat's the angular displacement over 0.16s? A. 20.5° B. 64.2° C. 128° D. 10.3°
B
A female softball pitcher releases the ball w/ an angular velocity of 35.28rad/s. It travels 12.5m 2 the batter in 0.372s. Wat's the distance from her shoulder 2 the ball? A. 1.05m B. .95m C. .92m D. 1.02m
Angle
A fig formed by 2 lines meeting @ a point, the vertex
A
A force of 300N is applied @ a point 1.3m from the axis of rotation, causing a revolving door 2 accelerate @ 309.4°/s2. Wat's the moment of inertia of the door from its axis of rotation? A. 72.2kg-m2 B. 1.26kg-m2 C. 2106kg-m2 D. 55.6kg-m2
B
A force of 393 N is exerted 20cm from the axis of rotation. Wat's the resulting moment of force? A. 786N-m B. 78.6N-m C. 19.7N-m D. 197N-m
Eccentric Force
A force that has a line of action that doesn't go thru the axis of rotation
Angle-Angle Diagram
A graph where the angle of 1 segment is plotted as a function of the angle of another segment
B
A gymnast wants 2 do 3 revs when she's airborne 4 1.77s. How fast must she rotate on avg? A. 1.69rad/s B. 10.65rad/s C. 33.4rad/s D. 18.8rad/s
A
A hammer thrower releases the hammer after reaching an angular velocity of 16.2rad/s. If the hammer is 180cm from the axis of rotation, wat's the linear velocity of the hammer @ release? A. 29.2m/s B. 11.1cm/s C. 2916m/s D. 9m/s
B
A kid's vertical takeoff velocity when jumping on a trampoline is 5.3m/s. Assuming takeoff & landing heights r the same, how long is the kid airborne? A. .29s B. .54s C. 1.08s D. 1.85s
Third-Class Lever
A lever system that the effort force is in btwn the fulcrum & the resistance force
First-Class Lever
A lever system that the fulcrum is in btwn the effort force & the resistance force
Second-Class Lever
A lever system where the resistance force is in btwn the effort force & the fulcrum
C
A merry-go-round has a radius of 3m. Kid A runs around, pushing it w/ a velocity of 4.0m/s. It takes kid B 4.71s 2 do 1rev when he pushes the merry-go-round. Which kid pushes it faster? A. kid A B. kid B C. They're = B. Not enough info
Parallel Axis Theorem
A method of calcing the moment of inertia abt an axis of rotation of an object if u know the moment of inertia abt a parallel axis
C
A running back is tackled w/ a force of 4100N by a linebacker weighing 1000N. Wat was the acceleration of the linebacker? A. 9.81m/s2 B. 102m/s2 C. 40.2m/s2 D. 4.1m/s2
Lever
A simple machine that magnifies force or speed of movement
Free Body Diagram
A sketch of an object or objects & all of the external forces & moments acting on the object
A
A softball player is only physically capable of swinging the bat @ 600°/s. Can she ↑ the velocity of the ball she hits w/o further training or using a dif bat? A. Yes, grasp the bat closer 2 the bottom so the radius of rotation ↑s. B. Yes, grasp the bat closer 2 the barrel so the radius of rotation ↓s. C. No, she'll have 2 ↑ angular velocity or ↑ the mass of the bat. D. Angular velocity doesn't affect tangential velocity of the ball after impact.
A
A swimmer finishes 10 laps in a 50m pool, finishing where she started. Wat were the linear distance & the linear displacement? A. Distance = 500m; displacement = 500m B. Distance = 500m; displacement = 0m C. Distance = 0m; displacement = 0m D. Distance = 0m; displacement = 500m
D
A top is spinning @ 5.6rev/s & starts decelerating @ 0.66rev/s2. How long will it take the object 2 stop? A. .12s B. 3.7s C. 6.6s D. 8.5s
D
A torque of 73N-m results in an object rotating 52.72° in .86s. How much angular work was done? A. 4476J B. 3850J C. 78.1J D. 67.2J
C
A triple jumper needs a velocity of 9.2m/s 2 make a gud jump. If he's accelerating @ 1.65m/s2, how much time does he need 2 reach the velocity? A. 4.58s B. 5.71s C. 3.5s D. 5.58s
Form Drag
A type of fluid resistance from a pressure dif in the fluid btwn dif sides of the object
Surface Drag
A type of fluid resistance resulting from friction btwn the surface of the object & the fluid
Degree
A unit of angular measurement- 1/360 of a rev
Revolution
A unit of measurement that describes 1 full cycle of a rotating bod
A
A vaulter is trying 2 reach a velocity of 7m/s @ the end of a 14m runway. How fast must he accelerate? A. .50m/s2 B. 1.75m/s2 C. 2m/s2 D. 3.5m/s2
Angular Kinetics
An area of mechanics involving the causes of angular motion, mainly torques
B
An ice skater rotating around a vertical axis ↓s in angular velocity from 450°/s 2 378°/s in 9.6s. Find the angular acceleration. A. −7.5rad/s2 B. −0.13rad/s2 C. 7.5°/s2 D. −72°/s2
Force Platform
An instrument used 2 sense & record the dynamic GRFs
A
An object has a moment of inertia of 184kg-m2. A torque of 84N-m is applied 2 the object. Wat's the angular acceleration? A. 2.19rad/s2 B. 15460rad/s2 C. .46rad/s2 D. 125rad/s2
E
An object is being pushed by a stick horizontally across a table @ a constant velocity. Which is (are) true? A. Linear acceleration = 0. B. The applied force is = 2 the kinetic frictional force. C. The applied force = 0. D. All of the above E. Both a & b
B
An object is spinning @ a constant angular velocity of 1000°/s. If it spins 4 2s, wat's the angular distance traveled? A. 2000rad B. 34.9rad C. 500rad D. 8.73rad
Lines of Action
An unbounded imaginary line going thru a force vector
Static Analysis
Analysis of the forces & torques acting on an object when they sum 2 0. This occurs whenever the object isn't moving or moving w/ constant velocity
Absolute Angle
Angle of a segment as measured from the right horizontal that describes the orientation of the segment in space
Separated Flow
As the relative speed of an object moving thru a fluid ↑s, the air molecules behind the object tend 2 separate leaving an air pocket or region of ↓ pressure
C
Calc the moment of inertia of a bat abt its proximal end if its mass is 2.1kg & has a radius of gyration of 0.58 & a length of .869m. A. .614kg-m2 B. .920kg-m2 C. .533kg-m2 D. 1.12kg-m2
C
Calc the height of the COM above its starting height during a squat jump based on the following info: BW = 777N, total vertical force = 899N, & time of force application = .93s. A. .21m B. .12m C. .10m D. .073m
D
Calc the height of the trajectory from the point of release. A. 6.06m B. 6.66m C. 17.5m D. 18.1m
C
Calc the relative angle @ the knee & the absolute angles of the thigh given the following positions in m: hip (2.000, 1.905), knee (2.122, 1.642), & ankle (1.897, 1.210). A. Abs = −65.1°; rel = −52.4° B. Abs = 114.9°; rel = −127.6° C. Abs = 114.9°; rel = 52.4° D. Abs = 24.9°; rel = 37.6°
A
Calc the rotational E of a segment, given mass of the segment is 2.2kg, moment of inertia is .57 kg-m2, & angular velocity is 25rad/s. A. 178J B. 7.13J C. 356J D. 102J
A
Calc the takeoff velocity 4 a jump based on the following hypothetical graph (jumper's weight = 700N). A. 1.40m/s B. .71m/s C. 16.1m/s D. 1.96m/s * THERE'S A DIAGRAM IN THIS QUESTION BUT I CAN'T INCLUDE IT IN QUIZLET*
C
Calc the time 2 peak height. A. 1.11s B. 1.59s C. 2.15s D. 2.22s
C
Calc the time from the apex 2 the ground. A. 1.63s B. 1.28s C. 1.99s D. 2.02s
D
Calc the total flight time. A. 3.13s B. 3.1s C. 2.39s D. 2.74s
A
Calc the total height of the parabola. A. 20.1m B. 19.5m C. 8.6m D. 8m
C
Calc the vertical & horizontal velocity components. A. vx = 15.56m/s, vy = 10.9m/s B. vx = 10.9m/s, vy = 15.56m/s C. vx = 30.19m/s, vy = 21.14m/s D. vx = 21.14m/s, vy = 30.19m/s
B
Combine the following 2 velocity vectors 2 find the resultant vector. Vector A = 5.5m/s @ 210° & vector B = 10.7units @ 82°. A. Resultant = 8.51m/s; θ = 67.4° B. Resultant = 8.51m/s; θ = 112.6° C. Resultant = 72.3m/s; θ = 22.6° D. Resultant = 72.3m/s; θ = 112.6°
A
Consider the following diagram of the biceps brachii acting on the radius in 2 joint positions. The angle of pull of the biceps brachii force ∆s from 15° 2 30°. If the muscle force is 1600N & the attachmentsite of the muscle is .042m from the joint axis, wat's the ∆ in joint torque applied by the biceps brachii from 15° 2 30°? A. 16.2N-m B. 17.4N-m C. 33.6N-m D. 67.2N-m * THERE'S A FIG IN THIS QUESTION, BUT I COULDN'T PUT IT IN THE QUIZLET*
C
Consider the following free bod diagram. Using static analysis, solve 4 Achilles tendon force that will put this system in equilibrium if d1 is .043m, d2 is .041m, & d3 is .126m. A. 239N B. 5578N C. 5557N D. 10.3N * THERE'S A FIG IN THIS QUESTION, BUT I COULDN'T PUT IT IN THE QUIZLET*
B
Consider the following free bod diagram. Using static analysis, solve 4 the horizontal & vertical forces of C that will maintain this system in equilibrium if A = 331N, B = 79N, and W = 50N. A. Fy = 342.5N; Fx = 59.6N B. Fy = -59.6N; Fx = -342.5N C. Fy = 59.6N; Fx =342.5N D. Fy = -9.6N; Fx = -342.5N * THERE'S A DIAGRAM IN THIS QUESTION BUT I CAN'T INCLUDE IT IN QUIZLET*
B
Consider the following free bod diagram. Using static analysis, solve 4 the moment @ the elbow if d1 is .039m, d2 is .142m, & d3 is .450m. Wat's the net muscle force? A. 2957N B. 2393N C. 93.3N D. 1084N * THERE'S A FIG IN THIS QUESTION, BUT I COULDN'T PUT IT IN THE QUIZLET*
A
Consider the following free bod diagram. Using static analysis, solve 4 the muscle torque that will put this system in equilibrium, given mass of the leg & foot is 5.4kg; distance from the knee joint 2 the COM of the leg-foot system .232m; weight of the barbell 150N; & distance from the knee joint 2 the COM of the barbell .514m. A. 89.4N-m B. 64.8N-m C. 78.4N-m D. Not enough info 2 solve N-m * THERE'S A FIG IN THIS QUESTION, BUT I COULDN'T PUT IT IN THE QUIZLET*
C
Convert the polar coordinates of (202, 202°) 2 rectangular coordinates. A. (−187.3,−75.7) B. (−75.7, −187.3) C. (81.6, 81.6) D. (−187.3, 75.7)
B
Convert the rectangular coordinates of (111, 222) 2 polar coordinates. A. (192.3, 26.6°) B. (192.3, 63.4°) C. (248.2, 26.6°) D. (248.2, 63.4°)
D
During a knee extension exercise, the knee extensor muscle group is applying a torque of 250N-m in an isometric contraction against the machine pad. If the knee joint angle is being held @ an angle of 38° below the horizontal & the machine pad is .35m from the knee joint, how much force is being applied @ the pad? A. 250N B. 1160N C. 714N D. 906.5N
C
During a volleyball serve, the ball leaves the hand w/ an initial velocity of 10m/s angled 41° from the horizontal. Wat r the horizontal & vertical velocities of the ball? A. vx = 7.5m/s; vy = 6.6m/s B. vx = 6.6m/s; vy = 7.5m/s C. vx = 5.2m/s; vy = 8.6m/s D. vx = 8.6m/s; vy = 5.2m/s
C
During an elbow flexion exercise, the relative angle @ the elbow is 103° @ 0.67s & 89° @ 0.75s. Wat's the avg angular velocity of the elbow? A. −5.0°/s B. 5.0°/s C. −175°/s D. 175°/s
A
During the support phase of walking, the absolute angle of the thigh has the following angular velocities: Calc the angular acceleration @ frame 39. A. 25.49rad/s2 B. 18.44rad/s2 C. 22.22rad/s2 D. 20.33rad/s2 * THERE'S A TABLE INCLUDED IN THIS QUESTION, BUT I COULDN'T PUT IT IN THE QUIZLET*
B
During walking, the knee joint makees 60N-m of extensor torque during the same interval of the stance phase when the knee joint moved from 8.02° of flexion 2 14.9° of flexion in .02s. Find the power of the knee joint muscles. A. −360W B. 360W C. 20640W D. −20640W
Unstable Equilibrium
Exists when, after a force or torque is applied, an object continues 2 displace from the original position
Stable Equilibrium
Exists when, after a force or torque is applied, an object returns 2 its original position
B
Fig 8.11 shows the path of a runner. If the runner starts & ends @ the end of each block, & if each block is a square w/ lengths of 180m, wat's the magnitude of the resultant displacement of the runner? A. 3600m B. 1080m C. 894m D. 805m
Impulse
Force ×ed by time or the area under a force by time curve
C
Given a right-Δ in quadrant I w/ hypotenuse = 28.8cm, side X = 1cm, find the length of side Y & the size of the other 2 angles. A. Side Y = 28.9cm, θ1 = 86.2°, θ2 = 3.9° B. Side Y = 26.9cm, θ1 = 86.0°, θ2 = 4.0° C. Side Y = 28.7cm, θ1 = 86.2°, θ2 = 3.8° D. Side Y = 30.7cm, θ1 = 86.5°, θ2 = 3.5°
D
Suppose sum1 moves from point s1 (1, 0) 2 point s2 (1, 11) 2 point s3 (−4, 4) & ends @ point s4 (2, −7). Wat r the horizontal, vertical, & resultant displacements? A. Horizontal = 11units; vertical = 14units; resulant = 7.1units B. Horizontal = 1unit; vertical = -7units; resulant = 7.1units C. Horizontal = 0unit; vertical = 8units; resulant = 8units D. Horizontal = 1unit; vertical = 7units; resulant = 25units
D
How much power is made in the horizontal direction by a force of 950N applied 2 an object @ an angle of 40°, causing the object 2 move horizontally 4m in 1.6s? A. 4658W B. 1527W C. 2375W D. 1819W
D
How much torque must b made by the hip flexors 2 hold an 80N ankle weight straight out @ a 90° position? The ankle weight is .73m from the hip joint. The thigh & leg weighs 130N. The moment arm 4 the hip flexors muscle is .08m. A. 58.4N-m B. 106N-m C. 1323N-m D. Not enough info
A
In the release phase of bowling, the bowler's arm & 4arm travel thru .24 & .28rad, in .03s. The length of the arm is .82m & the 4arm .51m. Wat % contribution 2 the tangential velocity of the ball cums from the rotation of the 4arm? A. 42% B. 58% C. 35% D. 65%
B
If a gymnast leaves the ground w/ a vertical velocity of 9.81m/s when doing a back flip, where in her trajectory will her COM b 1.0s later? A. Approaching the apex B. @ the apex C. ↓ing from the apex D. On the ground E. Not enough info
A
If a mass of 20.29kg acts ↓ward .29m from the axis of rotation on 1 end of a board & another force of 85N also acts ↓ward, wat's the moment arm of the 2nd force 2 balance this system? A. .68m B. 58m C. .069m D. The system isn't balanced; angular rotation will occur.
C
If a skater is rotating during a spin @ a constant angular velocity of 3.6rad/s 4 3.9s, wat's his angular acceleration? A. 14rad/s2 B. .92rad/s2 C. 0rad/s2 D. 1.1rad/s2
A
If sum1's leg exerts a force of 9N as it moves .4m in .2s, wat's the power made by the leg? A. 18 W B. 45 W C .72 W D. 4.5 W
A
If the 380N force is the anterior force applied by a foot on the ground when walking, wat will the person do? A. Fall, bc the frictional force is less than the applied force B. Fall, bc the frictional force causes the foot 2 "stick" 2 the ground bc it's greater than the anterior force C. Continue walking as norm since the frictional force is sufficient 2 prevent slipping D. Not enough info 2 answer
A
If the braking impulse in an anterior-posterior GRF by time curve for running is larger than the propulsion impulse, wat's the runner doing? A. Slowing B. Speeding C. Running w/ a constant velocity D. Not moving
B
If the leg is @ an angle of 35° below the horizontal, calc the moment arm of the torque caused by the weight of the leg, given that the distance 2 the COM of the leg 0.17m from the knee joint. A. .10m B. .14m C. .15m D. .17m
B
If the net moment @ a joint is 37.6N-m & the angular velocity @ the same instant in time is 4.40rad/s, wat's the angular power @ that joint? A. .12W B. 165W C. 8.55W D. 9480W
C
If the static coefficient of friction of a basketball shoe on a particular playing surface is .58 & the norm force is 911N, wat horizontal force is needed 2 cause the shoe 2 slide? A. <1,570N B. >306N C. >528N D. <528N
System
In a free-bod diagram, the object or objects under consideration. Could have a bod segment, a bod, or multi bods
Effort Arm
In a lever system the effort arm is the perpendicular distance btwn the line of action of the effort force vector & the axis of rotation
Resistance Arm
In a lever system the resistance arm is the perpendicular distance btwn the line of action of the resistance force vector & the axis of rotation
Resistance Force
In a lever system this is the force that's resisting movement
Dynamic Analysis
Mechanical analysis of an object while it's accelerating
Angular Motion
Motion abt an axis of rotation when dif regions of the same object don't move thru the same distance in the same time
Concurrent Forces
Multi forces that pass thru a common point
Noncontact Forces
Not a contact force
Neutral Equilibrium
Once an object is displaced the position stays constant
Equilibrium
Refers 2 1. a state of rest that multi forces acting on an object r balanced or 2. a state of balance
Stability
Refs 2 1. a state of balance or 2. the ability of a joint 2 resist dislocation
B
The COM of the following 3-point system w/ masses of 6, 5, & 4kg @ the coordinates (6,0), (5,5), & (−4, −3) is ____. A. 5.1, 4.1 B. 3, .87 C. 5.1, 2.5 D. 3, 1.4
Kinetics
Study of the forces that act on a system
A
Sum1 is running around a turn w/ a 17m radius @ 6.64m/s. Wat's the runner's centripetal acceleration? A. 2.59m/s2 B. 2.56m/s2 C. 0.39m/s2 D. 114m/s2
D
Sum1 lifts an 80kg weight 2 a height of 2.02m. When the weight is held overhead, wat's the PE? Wat's the KE? A. PE = 0N-m, KE = 162N-m B. PE = 162N-m, KE = 0N-m C. PE = 0N-m, KE = 1585N-m D. PE = 1585N-m, KE = 0N-m
D
Sum1 runs 20km in 89 mins. Wat was the avg speed in m/s? A. .27 B. .90 C. 3.75 D. 225
Rotational Friction
The friction bc 2 objects in contact that r rotating relative 2 each other
Angular Speed
The angular distance traveled divided by the time that the angular motion occurred
Angular Momentum
The angular quantity that ∆s when an angular impulse is applied 2 an object. Calc as the product of the moment of inertia & the angular velocity
Dynamics
The branch of mechanics that the system being studied does acceleration
Energy
The capacity 2 do work
Kinetic Energy
The capacity 2 do work that an object possesses bc of its velocity
Strain Energy
The capacity 2 do work that an object has bc of deformation of elastic materials
Rotational Kinetic Energy
The capacity 2 do work that an object has bc of its angular velocity
Potential Energy
The capacity 2 do work that an object has bc of its height
Turbulent Flow
The chaotic flow of a fluid that occurs behind an object moving thru a fluid. Turbulent flow occurs @ faster relative speeds & when the object isn't streamline
Centripetal Acceleration
The component of the linear acceleration directed 2 the axis of rotation
Propulsive Drag
The concept that drag forces can b used 2 propel the bod 4ward like in the freestyle stroke of swimming
Law of Conservation of Energy
The concept that indicates the total E of a system stays constant unless acted on by an external E source
Impulse-Momentum Relationship
The concept that it takes an impulse (force ×ed by time) 2 ∆ the momentum (mass ×ed by velocity) of an object
Conservation of Angular Momentum
The concept that the angular momentum of an object can't ∆ unless an external torque acts on it
Work-Energy Theorem
The concept that work done on an object will ∆ the E of that object
Pressure
The contact force per unit area of contact
Right-Hand Rule
The convention that designates the direction of an angular motion vector; the fingers of the right hand r curled in the direction of the rotation & the right thumb points in the direction of the vector
Kinetic Friction
The friction force btwn 2 objects that r moving relative 2 each other
Law of Cosines
The gen case of the Pythagorean theorem
Polarity
The direction of rotation designated as + or −
Radius of Gyration
The distance that an object w/ a particular moment of inertia would have 2 b located from an axis of rotation if it were a point mass
C
The final angular velocity of a golf swing was 400°/s w/ a constant angular acceleration of 501°/s2. How far did the club rotate? A. 101° B. 319° C. 160° D. 200°
Joint Reaction Force
The force @ a joint from the weights & inertial forces of the segments above the joint. It doesn't include the muscle forces
Bone-on-Bone Force
The force btwn 2 bones in the bod
D
The force parallel 2 a surface is 380N & the force perpendicular 2 the surface is 555N. The coefficient of friction is .66. Wat's the frictional force? A. 841N B. 617N C. 251N D. 366N
Fluid Resistance Force
The force resisting the movement of an object thru a fluid
Centripetal Force
The force that keeps an object moving w/ a constant angular speed
Friction
The force that resists motion when 2 objects slide against each other
Contact Force
The forces btwn 2 objects that r making contact w/ each other
B
The horizontal & vertical components of a force r 108 & 22N. Wat's the magnitude of the resultant vector? a. 130N b. 110N c. 106N d. 12148N
Passive Peak
The impact peak of a vertical GRF curve. It isn't under muscular control
Relative Angle (Joint Angle)
The included angle btwn 2 adjacent segments
A
The initial velocity of a baseball is 35m/s @ 10°. It was released @ a height of 2.0m. How ↑ above the ground & how far horizontally is the object when it's 1.12s n2 the flight? A. Vertical = 2.66m; horizontal = 38.61m B. Vertical = 0m; horizontal = 38.61m C. Vertical = 0.66m; horizontal = 6.81m D. Vertical = 2.66m; horizontal = 6.81m
Vertex
The intersection of 2 lines that form an angle
B
The kicking phase of a football punt takes place over .25s & includes hip flexion (89°) & knee extension (100°). If the thigh is .70m long & the leg .68m long, wat's the tangential velocity of the foot resulting from these movements? A. 4.7m/s B. 9.1m/s C. 4.3m/s D. 18.2m/s
Boundary Layer
The layer of air molecules closest 2 an object. This layer tends 2 move w/ the object
Radius of Rotation
The linear distance from the axis of rotation 2 a point on the rotating bod
Radian
The measure of an angle @ the center of a circle described by an arc = 2 the length of the radius of the circle (1rad = 57.3°)
Local Angular Momentum
The momentum abt a local axis of rotation. This is typ the momentum abt a segment COM
Remote Angular Momentum
The momentum abt a system axis of rotation. This is typ the momentum abt the COM of the bod
Fulcrum
The object giving the pivot point in a lever system
Active Peak
The peak of the running vertical GRF curve during midstance. It's the result of active contraction of muscle
Moment Arm
The perpendicular distance from the line of action of the force 2 the pivot point
Point of Application
The point that a force vector acts on an object
Point of Separation
The point that the boundary layer of fluid molecules separates from the object when the object is traveling thru the fluid
Center of Mass
The point that the distribution of mass sums 2 0
Center of Pressure
The point that the distribution of pressure sums 2 0
Center of Gravity
The point that the gravitational force is balanced. Corresponds 2 the COM in most cases
Inverse Dynamics
The process of calcing forces & moments based on the kinematics & anthrompometrics of a bod
Segmental Method
The process of calcing the COM of a system of masses by taking a weighted avg of the individual components
Work
The product of a force & the distance that the point of application travels in the direction of the force vector
Angular Power
The product of angular work & angular velocity or the rate of doing angular work
Power
The product of force & velocity
Torque
The product of the magnitude of a force & the perpendicular distance from the line of action of the force 2 the axis of rotation
Inertia
The property of a mass that resists a ∆ in velocity
Muscle Power
The quantity a muscle possesses bc of the tension & the contraction velocity
MA
The ratio of the effort arm 2 the resistance arm in a lever system. Indicates the advantage of the lever system
Coefficient of Friction
The ratio of the friction force to the norm force btwn 2 bods
Tangent
The ratio of the side opposite an angle 2 the adjacent angle in a right-∆
Moment of Inertia
The resistance of an object to ∆s in angular motion. Found by the mass & the distribution of mass
Laminar Flow
The smooth flow of a fluid over an object moving thru the fluid. Occurs @ slower relative speeds & when the object is streamline. Pressure dif is min
Linear Kinetics
The study of the cause of translation (forces)
Vector Composition
The summation of 2 or more vectors 2 get a resultant vector
Magnus Effect
The tendency of a spinning object 2 move in a curved path while moving thru a fluid
Angular Velocity
The time rate of ∆ of angular displacement
Moment of Force
The torque caused by an eccentric force
Angular Work
The torque ×ed by the angular distance that the object moves. Doing this on an object ∆s the angular E
Angular Impulse
The torque ×ed by the duration of the torque. Calc as the integral of the torque w/ respect 2 time
A
The work calc @ time 1 & time 2 was 925 & 998N-m. Calc the power if the time interval was .049s. A. 811W B. 18878W C. 39245W D. 1923W
Impact Peak
The ↑ frequency peak force that occurs when 2 objects collide fast
Tangential Velocity
The ∆ in linear position per unit time of a bod moving along a curved path
A
U r trying 2 make an ab crunch more hard. Which of the following will accomplish? A. Hold ur arms behind ur head vs across ur chest. B. Swing ur arms 2 ur legs as u crunch ↑ward. C. Place a weight on ur feet. D. U can't make a crunch more hard unless u hold additional weight.
D
U slide ↓ the same hill on a sled when (a) there's snow @ the bottom & (b) there's just grass @ the bottom when the hill levels off. Assuming u reached the bottom of the hill w/ the same velocity, y don't u travel as far b4 u cum 2 a stop when on the grass? A. It takes more work 2 slow in the snow B. U have less KE on the grass C. U do travel the same distance, it just takes u longer on the grass D. The work done by friction 2 slow u occurs faster on the grass
B
U stand on a 2% incline & later on a 10% incline. In which situation is frictional force l↓er? A. The 2% incline, bc the norm force is less B. The 10% incline, bc the norm force is less C. It stays constant bc ur mass & grav stay constant D. Incline doesn't affect the frictional force
D
Wat's the angular momentum if the force is 66N, the lever arm is 7.7m, & the time is 1.2s? A. 424kg-m2/s B. 79.2kg-m2/s C. 508kg-m2/s D. 610kg-m2/s
B
Wat's the avg angular velocity of the stick? A. 12.8rad/s B. 567°/s C. 10.9rad/s D. 623°/s
C
Wat's the linear distance moved by the end of the stick? A. 94m B. 77m C. 1.6m D. 1.3m
C
Wat's the pressure on the bottom of the foot 4 an 85kg person on the balls of 1 foot making contact over an area of ≈ 100cm2? A. 8500N/cm2 B. .85N/cm2 C. 8.34N/cm2 D. 83.4N/cm2
A
Wat's the tangential acceleration of the end of the stick? A. 145m/s2 B. 132m/s2 C. 36.3m/s2 D. 72.6m/s2
B
Wat's the tangential velocity of the end of the stick? A. 624m/s B. 10.9m/s C. 12.0m/s D. 14.1m/s
C
Wat's the torque made @ the elbow by a 206N force pulling on the 4arm @ an angle of 110° from the horizon @ a point 16.5cm from the elbow's axis of rotation? The 4arm is positioned horizontal 2 the ground. A. 1163N-m B. 11.6N-m C. 31.9N-m D. 3194N-m
C
Wat's the work done on the segment given the following info? The time btwn frames is .01s. A. 60.3J B. 8.4J C. 77.2J D. 42.8J * THERE'S A TABLE IN THIS QUESTION, BUT I COULDN'T PUT IT IN THE QUIZLET*
D
Wat's total E of the segment, given that mass is 3.9kg; vx is 1.45m/s; vy is 2.78m/s; moment of inertia is .0726kg-m2; angular velocity is 9rad/s; & the height of COM is .67m? A. 396.1J B. 66.91J C. 65.04J D. 47.74 J
C
Where is the COM of a segment in space if the proximal end is @ (213, 400) & the distal end is @ (378, 445) & the COM is 42.9% from the proximal end of the segment? A. 162, 191 B. 142, 381 C. 284, 419 D. 381, 142
C
Which is true of a cyclist's pedals? A. The angular velocity is 0 if his angular acceleration is 0. B. The angular displacement is always = 2 the angular distance traveled. C. The angular distance is always greater than or = 2 the angular displacement. D. Centripetal acceleration always points away from the axis of rotation.
D
Why do the deltoids need 2 make a greater torque when ur arm-4arm is closer 2 ur side vs straight out @ 90°? A. Bc the moment arm of the COM of the arm-4arm is larger. B. Bc the component of the weight of the arm-4arm that causes a moment is larger. C. The torque is the same bc the distance from the shoulder joint 2 the COM of the arm-forearm is constant. D. The torque is less bc the moment arm of the COM of the arm-4arm is less.
External Work
Work done by external forces
Internal Work
Work done by internal forces
Positive Work
Work that occurs when the force acting on an object is in the same direction as the motion
Negative Work
Work that occurs when the force acting on an object opposes the motion
