exam 1, 2 Flashcards
a free body diagram displays
a. the weight distribution of a body on a surface
b. the pressure distribution of a body on a surface
c. the mass distribution of a body
d. the forces acting on a body
e. none of the above
d
If two forces lying in the same plane are added together and the result is zero, which of the following is true of the forces?
a. They are opposite in direction.
b. They are equal in magnitude.
c. Both a and b are true.
d. none of the above
c
The force that acts parallel to an object in contact with a surface is called
a. friction force
b. normal contact force
c. internal force
d. colinear force
e. resolved force
a
A force can be
a. a push
b. a pull
c. either a or b
d. simultaneously a push and a pull
e. none of the above
c
A 90 kg weightlifter exerts a 1000 N force upward against a 50 kg barbell. How large is the net vertical force acting on the barbell?
a. 1050 N
b. 510 N
c. 1050 kg
d. 950 kg
e. 1490 N
b
Two teams are competing in a tug-of-war. George (170 lb), Laura (120 lb), and Jenna (110 lb) are on team A. The coefficient of static friction between their shoes and the floor is 0.40. Bill (230 lb), Hilary (140 lb), and Chelsea (130 lb) are on team B. The coefficient of static friction between their shoes and the floor is 0.30. Which team will be able to create more static friction force and thus be more likely to win the tug-of-war?
George’s team, static coefficient is greater, harder for them to move
to fully define a vector quantity, you must specify
a. length and magnitude
b. length and area
c. area and direction
d. direction and magnitude
e. none of the above
d
which of the following statements is true of the amount of horizontal force required to start in motion an object sitting on a horizontal surface
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 max kinetic friction force
d. it must be greater than the max static friction force
e. none of the above
d
which of the following, when present, is NOT an external force applied to a runner
a. gravitational force
b. weight
c. friction
d. muscle force
e. all of the above
c
Used to describe a force that __________ movement, traction is sometimes used in place of the term __________.
a. initiates; contact force
b. initiates; friction
c. initiates; muscle force
d. hinders; friction
e. hinders; contact force
b
Velocity is calculated as
a. distance divided by time
b. displacement divided by time
c. force divided by time
d. force times distance
e. force divided by distance
b
If an object’s initial coordinates are (3, 5, 0), and the final coordinates are (6, -2, -4), what is the object’s displacement?
a. 3 units right, 3 units down, and 4 units forward
b. 3 units left, 7 units up, and 4 units forward
c. 9 units right, 7 units down, and 4 units backward
d. 3 units right, 7 units down, and 4 units backward
e. need more information to calculate
d
At 3 s into a run, a football player is traveling at +3 m/s. Four seconds later, the player is traveling at -5 m/s. vi is equal to
a. 0 m/s
b. 3 m/s
c. 5 m/s
d. -3 m/s
e. -5 m/s
b
Units of acceleration are
a. s
b. m
c. m/s
d. m/s2
e. mi/h
d
Which of the following terms best describes linear motion along a curved line?
a. rectilinear
b. curvilinear
c. rotational
d. general
e. none of the above
b
When a runner has completed one full lap around a 400 m track, what is the runner’s displacement with respect to the starting position?
a. 400 m
b. 400 m multiplied by 2
c. zero
d. need more information to calculate
c
Which of the following is not a vector quantity?
a. distance
b. speed
c. neither a nor b
d. both a and b
d
What is the average speed of a cyclist who covers -15 mi in 30 min?
a. 5 mi/h
b. 10 mi/h
c. 30 mi/h
d. 60 mi/h
e. need more information to calculate
c
A swimmer is traveling with an average velocity of -3.2 m/s. How far does the swimmer travel in 3 s?
a. 1.1 m
b. 6.9 m
c. 9.6 m
d. A swimmer cannot travel in the negative direction.
e. need more information to calculate.
c
The horizontal velocity of Serena’s tennis serve is measured as 112 mi/h (50 m/s). Horizontally, the ball travels 82 ft (25 m) before reaching Venus (Serena’s opponent). If the ball didn’t slow down when it bounced or because of air resistance, how long would it take to reach Venus?
a. 0.25 s
b. 0.75 s
c. 0.50 s
d. 1.0 s
e. 2.0 s
c
Newton’s first law focuses on
a. action-reaction
b. acceleration
c. inertia
d. gravity
e. none of the above
c
Which of Newton’s laws is described by the equation F = ma?
a. first
b. second
c. third
d. fourth
e. law of gravitation
b
as the mass of an object increases, what happens to its inertia?
a. decrease
b. increase
c. stays the same
d. weighs more
e. mass and inertia are not related
b
if a body of constant mass is traveling with a constant velocity,
a. there must be no force acting on the body
b. there must be no net force acting on the body
c. there must be a force acting on the body
d. there must be a net force acting on the body
e. need more info
b
if a bag has a mass of 25kg, how much force must you apply vertically to lift it off of a baggage cart
a. less than 250N
b. 250N
c. greater than 250N
d. need more info
c
according to newtons third law, when two bodies collide,
a. the effects of the force applied to each body will be exactly the same
b. the effects of the force applied to each body will be exactly the same if the mass of each body is approx the same
c. the force applied to each body will be the same size
d. the force applied to each body will be the same size if the mass of each object is approx the same
c
a 500 N gymnast performs a stationary handstand on the high bar. how much force is exerted by the bar on the gymnasts hands
a. 50N
b. 100N
c. 500N
d. 2500N
e. need more info
c
the product of a force and the time during which the force acts on a body defines
a. linear momentum
b. linear velocity
c. linear acceleration
d. linear impulse
e. linear displacement
d
if you increase the time during which a constant force is applied to an object, what effect foes this have on the impulse given to the object
a. increases impulse
b. decreases impulse
c. doesn’t affect impulse
d. causes impulse to equal zero
e. none of the above
a
power is equal to
a. the act of force a muscle can generate
b. force times distance
c. work
d. force times displacement divided by time
e. none of the above
d
mechanical work is performed in all of these types of muscle activity (contraction) except for
a. isometric
b. concentric
c. eccentric
d. mechanical work is performed in all of the above
e. mechanical work is not performed in any of the above
a
when catching a baseball or softball with a glove
a. the ball performs positive work on the glove, and the glove performs negative work on the ball
b. the ball performs negative work on the glove and the glove performs positive work on the ball
c. positive work is performed on both the ball and glove
d. negative work is performed on both the ball and glove
e. no work is performed since the work on the ball and the work on the glove cancel each other out
a
a person performs a bench press. the bars mass is 50kg. when this persons arms are extended the bar is .6m above the starting point. how much work did the person do to push the bar off his chest to full extension of his arms
a. 0Nm
b. 200Nm
c. -300Nm
d. 600Nm
e. -600Nm
b
kinetic energy is the energy
a. due to deformation
b. due to motion
c. due to position
d. due to weight
e. kids use to run around a room
b
gravitational potential energy is the energy
a. due to deformation
b. due to motion relative to the earth
c. due to the position relative to the earth
d. due to weight
e. kids use to run around a room
c
during the pitching motion, a baseball pitcher exerted an avg horizontal force of 80N against the .15kg baseball while moving it through a horizontal displacement of 2.0m before release. the amount of work performed by the pitcher on the baseball was
a. 40J
b. 80J
c. 82J
d. 160J
e. 320J
d
if a 25 kg child climbs two steps of 20cm each, the work performed is
a. 10Nm
b. 100Nm
c. 1000Nm
d. 10,000Nm
e. need more info
b
the capacity for doing work that a body possesses because of its position or configuration is known as
a. potential energy
b. kinetic energy
c. moment of inertia
d. power
e. torque
a
the soft foam pit is used for landing during the pole vault. the foam pit cushions the landing of the vaulter by
a. reducing the friction encountered
b. reducing the displacement during the landing
c. increasing the friction encountered
d. increasing the displacement during the landing
e. none of the above
d
if an athlete moves faster, what happens to her momentum
a. increase
b. decrease
c. velocity has no impact on momentum
d. momentum equals 0
e. converts to impulse
a
the moment arm is defined as
a. the distance from the POA of a force to a specified axis of rotation
b. the distance from the line of action of a force to a specified axis of rotation
c. the perpendicular distance from the line of action of a force to a specified axis of rotation
d. all of the above
e. none of the above
c
torque is defined as
a. the tendency of a force to cause rotation
b. the turning effect of a force
c. the product of force and moment arm
d. all of the above
e. none of the above
d
two forces acting on an object to cause only rotation of the object create
a. force couple
b. negative forces
c. negative torques
d. positive torques
e. none of the above
a
what is the torque if a 50N force is applied 2m from the axis of rotation
a. 200Nm
b. 100Nm
c. 50Nm
d. 25Nm
e. 10Nm
b
as a joint is moved through its range of motion when strength training with free weights, such as doing the arm curl, the moment arm for the muscle crossing the joint will get
a. longer
b. shorter
c. either a or b
d. none of the above
c
if the moment arm is 5cm, and the force is 100N, the magnitude of the torque will be
a. 5Nm
b. 50Nm
c. 500Nm
d. 5000Nm
e. need more info
a
for any given muscle, the moment arm is largest when the angle of muscle pull on the bone is closest to
a. 0 degrees
b. 45
c. 90
d. 180
e. depends on the segment
c
in the average female, the COG is located
a. higher than the avg male
b. near the sternum
c. in the same place as the avg male
d. lower than the avg male
d
stability may be increased by
a. raising center of mass
b. decreasing number of contact points in the base of support
c. widening the base of support perpendicular to any oncoming force
d. leaning away from an oncoming force
e. none of the above
e
what happens to your COG when you add a 200 N suitcase to your hand held out to your side
a. shift in direction of suitcase
b. shifts in the direction opposite of suitcase
c. does not move
d. moves outside your body
e. need more info
a
which of the following is not a unit of angular displacement
a. radian
b. revolution
c. degree
d. watt
e. all of the above are units
d
an angle formed between two body segments is an example of
a. absolute angle
b. relative angle
c. double jointed angle
d. goniometric angle
e. radial angle
b
the anglar distance covered by a rotating object will always be
a. greater than the angular displacement by the object
b. smaller than the angular displacement covered by the object
c. at least equal to, if not greater than, the angular displacement covered by the object
d. at least equal to, if not smaller than, the angular displacement covered by the object
e. the angular distance depends on the radius
c
for a rotating object, the acceleration directed toward the center of rotation is called
a. tangential acceleration
b. rotary acceleration
c. centrifugal acceleration
d. linear acceleration
e. centripetal acceleration
e
which plane is perpendicular to the longitudinal axis
a. frontal
b. sagittal
c. transverse
d. oblique
e. vertical
c
a person riding a bicycle forward in a straight line would be moving in the
a. transverse plane
b. sagittal plane
c. frontal plane
d. AP plane
e. diagonal plane
b
when cycling forward in a straight line, the knee is rotating about a(n) ____ axis
a. longitudinal
b. vertical
c. anteroposterior
d. transverse
e. vertical
d
which of the following motions occurs primarily in the sagittal plane
a. running
b. a cartwheel
c. pirouette
d. all of the above
e. none of the above
a
which of the following motions occurs primarily in the transverse (horizontal) plane
a. running
b. a cartwheel
c. pirouette
d. all of the above
e. none of the above
c
in anatomical terminology, the front portion of the body is called
a. superior
b. inferior
c. anterior
d. posterior
e. none of the above
c
an example of a rotation about the longitudinal axis is a
a. front walk over
b. twist
c. somersault
d. cartwheel
e. jumping jack
b
by convention, positive angular direction is
a. clockwise
b. counterclockwose
c. always in the direction of flexion
d. always in the direction of extension
e. semicircular
b
a gymnast dismounts the uneven parallel bars with some angular momentum about her transverse axis. just after release, she is in a piked position. she then extends into a layout position before she lands. what happens as a result of this action
a. her moment of inertia increases and she rotates slower
b. her angular momentum decreases
c. her angular momentum increases
d. her moment of inertia decreases as she rotates faster
e. none of the above
a
when knee flexion is increased during running, the moment of inertia of the lower extremity about the hip is
a. increased
b. decreased
c. remains the same
d. depends on the anthropometric characteristics of the leg
e. moment of inertia cannot be measured about the hip
b
angular impulse is the product of
a. force and the time that force is applied
b. torque and the time that torque is applied
c. angular inertia and angular momentum
d. mass and angular velocity
e. force and torque
b
as an objects mass increases, what happens to its moment of inertia
a. increase
b. decrease
c. mass has no influence on moment of inertia
d. it changes the location of mass
e. this depends on how the added mass is distributed
e
in the equation for moment of inertia, which variable is most influential
a. mass
b. impulse
c. radius of gyration
d. center of gravity
e. all are equally influential
c
the SI unit for torque are
a. ft*lb
b. N
c. Nm
d. PSI
e. none of the above
c
what is the relationship between torque and angular acceleration
a. the greater the torque acting on the axis of rotation, the greater the angular acceleration of a given body
b. the greater the torque acting at the axis of rotation, the lower the angular acceleration of a give body
c. the lower the torque acting at the axis of rotation, the greater the angular acceleration of a given body
d. torque and angular acceleration are not related
a
when a body is completely motionless, it is considered to be
a. in dynamic equilibrium
b. in static equilibrium
c. undergoing positive acceleration
d. undergoing negative acceleration
e. a body is never motionless
b
the statement “a rotating body will maintain a state of constant angular motion unless acted on by an external torque” refers to
a. newtons 1st law
b. newtons 2nd law
c. newtons 3rd law
d. newtons 4th law
e. newtons torque law
a
a diver attempt a 1.5 front flip in a tuck position off the 1m board but only rotates 1.25 times. which of the following suggestions is not appropriate for the diver
a. jump higher
b. tuck looser
c. tuck sooner
d. release tuck later
e. generate more angular momentum going into the dive
b
You are coaching a Little League baseball team. One of your players is having a hard time hitting the ball. He does a good job of choosing which pitches to swing at, but he keeps missing because his bat doesn’t get around fast enough. What would you suggest that he do (give one suggestion)? Explain the reason for your suggestion.
choke up on the bat or choose a lighter, shorter bat. both of these suggestions reduce the moment of inertia of the bat about the swing axis
a ____ angular velocity of a football, flying disc, or discus contributes to a ____ flight of the implement
a. faster, less stable
b. slower, less stable
c. faster, more stable
d. slower, more stable
e. b and c
e
the principle or law used to describe lift is called
a. archimedes principle
b. Bernoullis principle
c. Wolffs law
d. pascals law
e. newtons principle
b
the vertical force that always acts upward is
a. gravity
b. acceleration
c. drag force
d. turbulance
e. buoyant force
e
which shape is most conductive to optimizing lift
a. sphere
b. foil
c. oblong
d. rectangle
e. square
b
which form of drag would have the greatest effect on a swimmer performing the crawl (freestyle) stroke in a smooth ocean
a. force drag
b. form drag
c. wave drag
d. pressure drag
e. shark drag
b
for a submerged object, the buoyant force acts as the
a. COG
b. center of mass
c. radius of rotation
d. center of volume
e. all of the above
d
the concept that explains how a spinning baseball changes direction is called
a. Pedros theory
b. the Bourne identity
c. angular impulse
d. radius of gyration
e. Magnus effect
e
In which conditions would the effects of air resistance be more significant: in a high-altitude venue on a hot day, or in a low-altitude venue on a cool day?
low altitude, cool day
water pressure ___ with depth. pressure is defined as ____
a. increases linearly, force per unit area
b. decreases linearly, force per unit area
c. increases vertically, buoyant force
d. decreases vertically, buoyant force
e. increases linearly, the weight go the fluid displaced by the object
a
when we consider the dynamic fluid forces acting on an object, we must take into account the velocity of the object as well as the velocity of the fluid itself
true or false
true
the size of the surface drag is affected by
a. the coefficient of drag
b. density of the fluid
c. cross sectional area of the object
d. square of the relative velocity
e. all of the above
e
a lift force can be directed upward, downward or in any direction that is perpendicular to the fluid flow
true or false
true
the wind blowing in the face of a 55kg distance runner will have the same effect as the same wind blowing in the face of a 75kg distance runner
true or false
false
when applying rigid-body mechanics to the study of human beings, which assumption is made
a. the body does not deform by bending, stretching or compressing
b. the segments are fixable links
c. the joints provide friction during movement
d. the body deforms by bending, stretching or compressing
e. all of the above are assumed
a
when a stretched material does not return to its original shape, it is called
a. elastic
b. plastic
c. refractive
d. porous
e. stiff
b
which force exerts a pull on the body acted upon
a. shear
b. compression
c. tension
d. torsion
e. all of the above
c
which force exerts a squeezing effect on the body acted upon
a. shear
b. compression
c. tension
d. torsion
e. all of the above
b
a load that produces twisting of a body around its longitudinal axis is called a
a. shear load
b. tensile load
c. compressive load
d. torsion load
e. combined load
d
identify the true statement
a. increasing the surface area over which a force is distributed decreases the act of stress acting on the surface
b. decreasing the surface area over which a force is distributes decreases the act of stress acting on the surface
c. both a and b
d. neither a or b
a
how many square cm are in a square m
a. 100
b. 1000
c. 10000
d. 100000
e. 1000000
c
at 0 degree knee flexion, the contact area between the tibia and the femur is 1.6cm^2. if the compressive force across the tibiofemoral joint is 1350N, the mechanical stress (in MPa) would be calculated to be
a. 8.44
b. 84.37
c. 843.75
d. 8437.5
e. need more info
a
stress is defined as the
a. mass per unit volume
b. force per unit volume
c. force per unit area
d. displacement per unit time
e. force per unit mass
c
connective tissues such as tendon and ligament are ____, meaning that they do not have the same mechanical properties in every direction
a. ductile
b. crimped
c. isotropic
d. anisotropic
d
what component of bone is primarily responsible for its compressive strength
a. collagen
b. minerals
c. water
d. vitamins
e. marrow
b
bone is strongest in resisting
a. tensile stress
b. shear stress
c. compressive stress
d. bone is equally strong in resisting all types of stress
c
when articular cartilage is exposed to constant compressive stress, the strain in the cartilage will increase radially with time. this pattern is called
a. elasticity
b. creep
c. collagen
d. stress-strain curve
b
ligaments are less stiff and slightly weaker than tendons because
a. ligaments have more elastin and less aligned collagen fibers
b. ligaments have less elastin and more aligned collagen fibers
c. ligaments have a diff type of collagen fiber
d. ligaments have randomly arranged collagen fibers
a
