chapter 8

Question 1

when is a fluid force ignored

Answer 1

projectile motion

Question 2

when is a fluid force life-saving

Answer 2

skydiving

Question 3

the force due to immersion in a fluid

Answer 3

buoyant force

Question 4

is a low body fat or high body fat person more likely to float

Answer 4

high

Question 5

magnitude of buoyancy is related to

Answer 5

size, how much is immersed

Question 6

direction of buoyancy

Answer 6

always acts vertically upward

Question 7

buoyant force magnitude equal to ______ displaced by object

Answer 7

weight of the volume of fluid

Question 8

more water displaced=___buoyant force

Answer 8

greater

Question 9

if weight of object >weight of water displaced

Answer 9

sink

Question 10

if weight of object = weight of water displaced

Answer 10

float

Question 11

if weight of object < weight of water displaced

Answer 11

rise

Question 12

ratio of weight of object to weight of the same volume of water

Answer 12

specific gravity

Question 13

if specific gravity <1, object

Answer 13

float

Question 14

if specific gravity > 1, object

Answer 14

sinks

Question 15

ratio of mass and volume

Answer 15

density

Question 16

specific density of bone and muscle

Answer 16

> 1, sink

Question 17

specific density of fat

Answer 17

<1, float

Question 18

Air in lungs decreases

Answer 18

specific density of the body

Question 19

Swimming: weight and buoyant forces not aligned when legs are

Answer 19

horizontal

Question 20

legs sink, weight and torque become

Answer 20

colinear, no torque

Question 21

key to floating

Answer 21

weight and buoyant force must align before angular momentum becomes too great

Question 22

dynamic fluid force present when an object moves ____ or when fluid moves ____

Answer 22

within a fluid, past an immersed object

Question 23

fluid forces directly proportional to

Answer 23

density of fluid, square of the relative velocity between body and fluid

Question 24

fluid density and surface area are __ terms

Answer 24

linear

Question 25

relative velocity is a ___ term

Answer 25

squared

Question 26

double v --> __x dynamic fluid force

Answer 26

4

Question 27

you standing still, wind blowing against you at 5m/s; RV=

Answer 27

0-(-5)=5

Question 28

you running at 5m/s, no wind; RV=

Answer 28

5-0=5

Question 29

you running at 5m/s, wind blowing against you at 5m/s; RV=

Answer 29

5-(-5)=10

Question 30

you running at 5m/s, wind blowing behind you at 5m/s; RV=

Answer 30

5-5=0

Question 31

component of the resultant dynamic force that acts on an object in opposition to the relative motion of the object with respect to the fluid

Answer 31

drag force

Question 32

what variable is the most impactful in drag force

Answer 32

v

Question 33

___affects drag coefficient

Answer 33

shape

Question 34

drag forces slow down or speed up an object

Answer 34

slow down

Question 35

two ways drag force is produced

Answer 35

surface drag, form drag

Question 36

friction between fluid molecules and surface of the object

Answer 36

surface drag

Question 37

rougher surfaces create larger ___ forces

Answer 37

friction

Question 38

impact forces between the molecules and the object

Answer 38

form drag

Question 39

broad, flat leading surfaces of an object create larger __ forces

Answer 39

impact

Question 40

if the fluid molecules stay close to the surface of the object at the LEADING surface forms grad force pusing towards the _____

Answer 40

rear

Question 41

if the fluid molecules stay close to the surface of the object at the TRAILING surfaceform drag forces pushing towards the

Answer 41

front

Question 42

when molecules stay close to the surface

Answer 42

laminar flow

Question 43

when molecules separate from the surface

Answer 43

turbulent flow

Question 44

how to reduce drag coefficient

Answer 44

make body surface, clothing, equipment smooth streamline the shape of the body and equipment reduce total SA exposed to flow

Question 45

form drag greater at ___ velocity surface drag greater at ___ velocity

Answer 45

faster slower

Question 46

how much drag comes from a persons body

Answer 46

70%

Question 47

how is drag force beneficial in rowing

Answer 47

paddles and oars create drag force to propel the boat or shell

Question 48

how is drag force beneficial in skydiving

Answer 48

parachutes use drag force to make landing safe

Question 49

when is drag force beneficial in water exercise

Answer 49

rehab and cross-training

Question 50

lift is ___up

Answer 50

not always

Question 51

component of the resultant dynamic force on the object acting perpendicular to the relative motion

Answer 51

lift force

Question 52

lift force changes direction of ___ of the object in the fluid

Answer 52

relative motion

Question 53

lift force can be directed in ___ direction ____ to fluid flow

Answer 53

any perpendicular

Question 54

lift force relation to which of newtons laws

Answer 54

3rd law

Question 55

faster moving fluids produce less force laterally than do slower moving fluids

Answer 55

bernoullis principle

Question 56

airfoil

Answer 56

object with two surfaces aligned with the fluid flow one surface more curved

Question 57

fluid moves faster over flatter or curved surface

Answer 57

curved

Question 58

curved surface=___ fluid =____perpendicular force

Answer 58

faster, less

Question 59

flatter surface = __ fluid= ___perpendicular force

Answer 59

slower, more

Question 60

lift force is the net effect between

Answer 60

unequal perpendicular forces

Question 61

Magnus effect

Answer 61

lift force acts on a spinning ball

Question 62

topspin

Answer 62

upper surface has forward velocity relative to center of ball lower surface has backward velocity

Question 63

lift force acts___ on a ball with topspin, acts ___ on a ball with backspin

Answer 63

down, up

Question 64

curveball in baseball

Answer 64

sidespin creates lift force sideways on a ball

Question 65

dynamic fluid is the resultant of which 2 forces

Answer 65

lift and drag

Question 66

center of pressure is the

Answer 66

point of application of the force

Question 67

if center of pressure and cg are not aligned

Answer 67

torque is created