- All athletic events take place in fluid. Fluid dynamics studies the effects of human movement and projectiles through these fluid forces.

sisterpurpleMechanics

Oct 24, 2013 (4 years and 17 days ago)

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Fluid Mechanics

Read pg 150
-
157 of text and answer the following questions:

1)

What does fluid dynamics study?

-

All athletic events take place in fluid. Fluid dynamics studies the effects of human
movement and projectiles through these fluid forces.

2)

Drag an
d lift forces are what to each other?

-

Perpendicular


3)

What is flow velocity?

-

The motion of fluid flowing past an object or motion of object through the fluid.

4)

What is drag? What is the difference between profile drag and skin
-
friction drag?

-

Resistance
through fluid

-

Profile drag is drag caused by shape of object

-

Skin
-
friction drag is drag caused by the roughness of a surface

5)

What are both skin
-
friction and profile drag proportional to
? Which most often occurs
in sport?

-

Skin
-
friction and profile drag are
proportional to relative flow velocity, cross
-
sectional area, shape of object, smoothness of surface, and density of liquid

-

Profile drag is the source of most drag in sport

6)

What is the difference between laminar flow and turbulent flow?

-

Laminar flow is smo
oth and layered

-

Turbulent flow is disordered, eddied,
and non
-
layered

7)

Why does turbulence increase the amount of work done on an object?

-

The region of low pressure created by turbulence must be carried along

8)

Describe how shape and equipment design help s
peed skaters and lugers overcome
drag?

-

Crouch, egg shape, arms back (speedskaters)

-

Helmet shape, sled shape

9)

Where can lift forces be directed?

-

Up (discus, ski jumpers), down (topspin), sideways (curveball)

10)

How does lift occur?

-

Air flows faster over one

side of an object, creating a difference in pressure

11)

What is Bernoulli’s principle?

-

Movement occurs from area of high pressure to area of low pressure



12)

What is the angle of attack? What is the stall angle?

-

Angle of attack is the tilt of an object relat
ive to flow velocity. Allows object to
lift and remain airborne longer

-

Stall angle is the angle at which the drag force overcomes the lift force
. Object
will fall at this point.

13)

Describe the Magnus effect.

-

Spinning ball creates turbulence

on one side
, tu
rbulence creates low pressure area,
object moves from area of high pressure to area of low pressure

14)

Draw a simple diagram that illustrates the Magnus effect. (see. Fig. 7.16)

15)

How does topspin/backspin affect horizontal distance?

-

Topspin shortens horizont
al distance, and backspin lengthens horizontal distance

16)

What direction does a ball break with sidespin?

-

The direction the ball is spinning

17)

Why is the Magnus effect most readily seen in tennis, golf, ping
-
pong, baseball?

-

Objects have large enough cross
-
sectional area, are light

& small

(can spin more,
increasing flow velocity), have rough surfaces (tennis, baseball, golf)

18)

How does the design of a baseball allow for a curveball to be thrown?

-

Stitches



















Wiffeball
-

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tch?v=bYdR5kMzqJo