- 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 (3 years and 9 months 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