chapter 15 Flashcards
Buoyant force is directly related to what?
A. mass
B. weight
C. volume
D. density
C. volume
Which of the following quantities are forces?
A. friction
B. buoyancy
C. weight
D. all of the above
D. all of the above
“A flow characterized by smooth, parallel layers of fluid” is the definition of which of the following?
A. relative velocity
B. turbulent flow
C. laminar flow
D. none of the above
C. laminar flow
Which of the following is not true about drag?
A. it is a force caused by the action of a fluid
B. it is affected by surface area
C. it is affected by the density of the fluid
D. all of the above are true
D. all of the above are true
The theoretical square law is related to which of the following?
A. friction
B. lift force
C. drag
D. none of the above
C. drag
Which of the following factors affects skin friction drag?
A. increase in the relative velocity of fluid flow
B. the surface area of the body over which the flow occurs
C. the viscosity of the fluid
D. all of the above
D. all of the above
Which of the following describes the drag created by a pressure differential between the lead and rear sides of a body moving through a fluid?
A. form drag
B. profile drag
C. surface drag
D. both A and B above
D. both A and B above
The nature of the boundary layer depends on which of the following?
A. the roughness of the body’s surface
B. the body’s velocity relative to flow
C. both A and B
D. none of the above
D. none of the above
Which of the following terms describes a force acting on a body in a fluid in a direction perpendicular to the fluid flow?
A. wave drag
B. surface drag
C. form drag
D. lift
D. lift
Which of the following factors affects lift force?
A. relative velocity of the fluid
B. fluid density
C. size, shape, and orientation of the body
D. all of the above
D. all of the above
Lift force occurs in which direction?
A. up
B. down
C. sideways
D. all of the above
D. all of the above
Which of the following quantities affects a discus as it travels through the air?
A. surface drag
B. lift force
C. both A and B
D. neither A nor B
C. both A and B
Which type of fluid resistance is likely to be greatest on a swimmer in the ocean at a fast speed?
A. skin friction
B. profile drag
C. wave drag
D. none of the above
C. wave drag
Relative velocity of the fluid affects which of the following?
A. skin friction
B. wave drag
C. lift force C
D. all of the above
D. all of the above
Which of the following statements is true of the Magnus force?
A. It is created by spin on a ball.
B. It is created by a pressure differential.
C. Both A and B are true.
D. Neither A nor B is true.
C. Both A and B are true.
The theory attributing propulsion in swimming to Newton’s third law is what?
A. the propulsive drag theory
B. the propulsive lift theory
C. the vortex theory
D. none of the above
A. the propulsive drag theory
The inverse relationship between relative velocity and relative pressure in a fluid is what?
A. Archimedes principle
B. Bernoulli principle
C. magnus principle
D. none of the above
B. Bernoulli principle
Which of the following explains buoyancy?
A. Archimedes principle
B. Bernoulli principle
C. magnus principle
D. none of the above
A. Archimedes principle
Fresh water is more dense than which of the following?
A. sea water
B. air
C. muscle
D. none of the above
B. air
Which of the following is considered a fluid?
A. air
B. water
C. molasses
D. all of the above
D. all of the above
A man’s ability to float is most directly related to his what?
A. mass
B. weight
C. volume
D. density
D. density
Which of the following is defined “velocity of a body with respect to the velocity of the wind (or other surrounding fluid)”?
A. resultant velocity
B. absolute velocity
C. relative velocity
D. all of the above
C. relative velocity
Which of the following statements is accurate?
A. As a fluid becomes denser, it exerts greater forces on moving body.
B. As a fluid becomes denser, it becomes more viscous.
C. both A and B
D. none of the above
C. both A and B
Which of the following are inversely related?
A. density and volume
B. density and specific weight
C. specific weight and mass
D. mass and density
B. density and specific weight
Which of the following statements is always true?
A. center of volume is in the same place as center of mass
B. center of volume is in the same place as center of buoyancy
C. center of mass is in the same place as center of buoyancy
D. all of the above are true
B. center of volume is in the same place as center of buoyancy
For flotation to occur, which of the following must exist?
A. buoyant force must exceed weight
B. buoyant force must equal or exceed weight
C. weight must exceed buoyant force
D. weight must equal or exceed buoyant force
B. buoyant force must equal or exceed weight
Which two forces are always opposite in direction?
A. lift and drag
B. buoyancy and drag
C. buoyancy and weight
D. drag and weight
C. buoyancy and weight
Why were so many world records set at the 1968 Olympic Games in Mexico City?
A. higher altitude reduced VO2max
B. higher altitude reduced drag force
C. both A and B
D. none of the above
B. higher altitude reduced drag force
Total drag is greater for which athletes?
A. swimmers
B. runners
C. equal for swimmers and runners
D. need more information
A. swimmers
Which of the following is true regarding passive drag?
A. generated by a swimmer’s body size, shape, and position in the water
B. inversely related to a swimmer’s buoyancy
C. associated with the swimmer in motion
D. both A and B
E. all of the above
D. both A and B
Which of the following factors that affect skin drag, can athletes usually alter?
A. roughness of the body surface
B. amount of surface area in contact with the fluid
C. viscosity of the fluid
D. both A and B
E. all of the above
D. both A and B
How do dimples on a golf ball reduce form drag?
A. produce a turbulent boundary layer
B. produce a laminar boundary layer
C. both A and B D
. dimples do not reduce form drag
A. produce a turbulent boundary layer
“Drafting” can reduce which kind of drag?
A. skin friction
B. form drag
C. wave drag
D. all of the above
B. form drag
Which of the following is considered a foil shape?
A. human hand
B. discus
C. shot put
D. both A and B
E. all of the above
D. both A and B
Ski jumpers attempt to do which of the following?
A. increase lift and increase drag
B. increase lift and decrease drag
C. decrease lift and decrease drag
D. decrease lift and increase drag
B. increase lift and decrease drag
Which of the following statements is/are true?
A. Angle of attack and release angle both affect horizontal range.
B. Angle of attack and release angle are independent of each other.
C. Angle of attack and release angle are always equal.
D. both A and B
E. all of the above
D. both A and B
Topspin on a tennis ball will have what effect?
A. Ball will drop sooner.
B. Ball will rebound lower.
C. Ball will rebound faster.
D. both A and B
E. all of the above
E. all of the above
A curve ball pitch follows which path?
A. straight line with sudden break at the end
B. smooth arc
C. can be either A or B
D. none of the above
B. smooth arc
Golf clubs are designed to impart backspin, which affects the ball in what way?
A. increase in flight time
B. increase in range
C. both A and B
D. none of the above
C. both A and B
Which of the following acts in the same direction as body motion?
A. wave drag
B. propulsive drag
C. skin friction
D. all of the above
B. propulsive drag
angle of attack
angle between the longitudinal axis of a body and the direction of the final flow.
Archimedes’ principle
physical law stating that the buoyant force acting on a body is equal to the weight of the fluid displaced by the body.
Bernoulli principle
an expression of the inverse relationship between relative velocity and relative pressure in a fluid flow.
boundary layer
layer of fluid immediately adjacent to a body
center of volume
point around which a body’s volume is equally balanced and at which the buoyant force acts.
coefficient of drag
unitless number that is an index of a body’s ability to generate fluid resistance
coefficient of lift
unitless number that is an index of a body’s ability to generate lift.
fluid
substance that flows when subjected to a shear stress.
foil
shape capable of generating lift in the presence of a fluid flow.
Form drag, pressure drag, profile drag, profile drag,
resistance created by a pressure differential between the lead and rear sides of a body moving through a fluid.
laminar flow
flow characterized by smooth, parallel layers of fluid.
lift
force acting on a body in a fluid in a direction perpendicular to the fluid flow.
lift / drag ratio
the magnitude of the lift force divided by the magnitude of the total drag force acting on a body at a given time.
Magnus effect
deviation in the trajectory of a spinnning object toward the direction of spin, resulting from the Magnus Force.
Propulsive drag
force acting in the direction of a body’s motion.
propulsive drag theory
theory attributing propulsion in swimming to propulsive drag on the swimmer.
propulsive lift theory
theory attributing propulsion in swimming at least partially to lift acting on the swimmer.
relative velocity
velocity of a body with respect to the velocity of something else, such as the surrounding fluid.
Skin friction, surface drag, viscous drag
resistance derived from friction between adjacent layers of fluid near a body moving through the fluid.
Theoretical square law
drag increases approximately with the square of velocity when relative velocity is low.
turbulent flow
flow characterized by mixing of adjacent fluid layers.
wave drag
resistance created by the generation of waves at the interface between two different fluids, such as air and water.
