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PE - Biomechanics > Projectile motion > Flashcards

Projectile motion Flashcards

1
Q

What is the definition of fluid mechanics?

A

The study of forces acting upon a body travelling through water/air

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2
Q

What is air resistance?

A

Force opposing the direction of motion of an airborne object

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3
Q

What is drag?

A

Force opposing the direction of motion of a body travelling through a fluid

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4
Q

What factors affect air resistance/drag?

A 
Velocity
Frontal cross sectional area
Streamlining/shape
Surface characteristics
Temperature
Altitude/air density
Mass
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5
Q

How does velocity affect air resistance/drag?

A

The higher the velocity, the higher the AR/drag

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6
Q

How does frontal cross sectional area affect air resistance/drag?

A

The smaller the frontal cross sectional area the smaller the AR/drag

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7
Q

How does streamlining/shape affect air resistance/drag?

A

The more streamlined, the less AR/drag

The teardrop shape is the most streamlined

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8
Q

How does surface characteristics affect air resistance/drag?

A

The smoother the surface, the less AR/drag

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9
Q

How does temperature affect air resistance/drag?

A

The lower the temperature the more AR/drag as density of air increases

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10
Q

How does altitude/air density affect air resistance/drag?

A

The lower the air density/higher the altitude the less AR/Drag

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11
Q

How does mass affect air resistance/drag?

A

The higher the mass, the more AR/drag

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12
Q

Describe the speedo LZR swimming suite/its restrictions

A

Full body suite that is hydrophobic, reduces drag so increases velocity.
Must be above knee and below belly button (men)

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13
Q

Why was the spyder tripwire suite banned from skiing?

A

Reduce AR up to 40%
Banned because gave some performers an unfair advantage
Thin wire pulls pads in to reduce surface area and therefore, AR. Can still have ones that reduce AR by 20%.

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14
Q

Definition of projectile motion?

A

Motion of a body through the air following a curved flight path.

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15
Q

What is the definition of a projectile?

A

A body launched through the air and losing contact with a contact/ground surface.

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16
Q

What is the definition of a parabola?

A

A uniform curve symmetrical about its highest point

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17
Q

What force is dominant when the flight path is a true parabola?

A

Weight

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18
Q

What force is dominant when the flight path is non-parabolic?

A

Air resistance

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19
Q

How does air resistance affect the flight path of an object?

A

The greater the effect of AR the greater the projectile will deviate from a true parabolic flight path.

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20
Q

Why does a shot put have a parabolic flight path?

A

Weight is dominant.
Shot has a large mass.
Travels at a low velocity and has a smooth and small frontal cross sectional area so a small AR.

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21
Q

Why does a shuttlecock have a non parabolic flight path?

A

AR is the dominant force.
Shuttle has a small mass.
Travels at a high velocity and has a rough/large frontal cross sectional area so has a large AR

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22
Q

What affects the flight path of a projectile?

A

Speed of release
Angle of release
Height of release
Aerodynamic factors (Bernoulli/Magnus)

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23
Q

What is the primary factor affecting the horizontal distance travelled?

A

Speed of release

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24
Q

Which one of Newton’s laws links to speed of release?

A

Second law of acceleration

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25
Q

How do you link Newton’s second law to a projectile?

A

The greater the force applied to the projectile, the greater the change in momentum and acceleration of the projectile into the air at the point of release.

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26
Q

As acceleration of the projectile increases what happens to horizontal distance?

A

It increases.

Therefore, there is a greater importance for upper body strength to enable throwing related sports.

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27
Q

What is the optimum angle of release for projectiles released from the ground?

A

45 degrees

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28
Q

What happens if a projectile is released at less than 45 degrees from the ground?

A

Does not achieve sufficient height to maximise flight path time. Decrease height = decrease flight time = decrease distance.

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29
Q

What happens if a projectile is release at more than 45 degrees from the ground?

A

Reaches peak height too quickly and rapidly returns to ground. Increase height, increase flight time but decrease distance.

30
Q

What happens if a projectile is released at 90 degrees?

A

Body travels vertically upwards and straight down (0 meters)

31
Q

When is 45 degrees the optimal release angle?

A

When the release height is the same as the landing height eg long jump/chip shit in golf

32
Q

When is a release height of less than 45 degrees optimal?

A

When release height is above the landing height (Positive release angle) eg shot put

33
Q

When is a release height of more than 45 degrees optimal?

A

When the release height is below the landing height (negative release angle) eg golf bunker/basketball shot

34
Q

What is the Bernoulli principle?

A

The theory of how an additional lift force is created during flight based on the shape of a projectile

35
Q

What is the definition of lift force?

A

Additional force created from pressure gradients forming on opposite surfaces of an aerofoil moving through fluid.

36
Q

What direction does lift force act in?

A

Perpendicular to the direction of motion

37
Q

What is the effect of lift force on a projectile?

A

Increases potential flight time of a projectile and therefore the horizontal distance travelled

38
Q

What is the pressure when the velocity is high?

A

Low

39
Q

What is the pressure when the velocity is low?

A

High

40
Q

What affects the velocity of air passing an aerofoil?

A

The further the air has to travel, the faster the air must travel.

41
Q

How do you draw an air flow diagram?

A

Must show DOM arrow. 3 air flow lines above and below the projectile.
Airflow opposes DOM.
Closer together airflow lines = higher velocity of air.
Label velocity and pressure, above and below projectile.
Show lift force acting from centre of mass.

42
Q

What is the angle of attack?

A

The most favourable angle of release, of a projectile, to optimise lift force to increase flight time/horizontal distance.

43
Q

What is the definition of an aerofoil shape?

A

A streamlined shape with a curved upper surface and a flat lower surface.

44
Q

What happens if an aerofoil is inverted?

A

The Bernoulli lift force acts in a downwards direction

45
Q

What is the definition of an inverted aerofoil shape?

A

A streamlined shape with a curved lower surface and flatter upper surface

46
Q

What is the affect of downwards lift force on F1 cars?

A

Increased grip when cornering at high speeds

47
Q

What do the front wings do on an F1 car?

A

Funnel air downwards, increasing distance for air flow, increasing air flow velocity.

48
Q

What does the rear spoiler do on F1 cars?

A

Acts as an inverted aerofoil, decreases air velocity above which increases pressure.
Increases air velocity below which decreases pressure.

49
Q

What does a cyclists helmet, high seat and low handlebars create?

A

A flatter upper body surface to create a teardrop shape

50
Q

How does the teardrop shape help a cyclist?

A

It is a streamlined shape that reduces the frontal cross sectional area/air resistance and creates additional lift force

51
Q

How does increasing lift force help a cyclist?

A

Additional downwards force, increased effect of weight/reaction force with the track. Increases friction so both grip and velocity are maximized.

52
Q

What is the definition of the Magnus effect?

A

When a lift force is applied to a spinning projectile

Causes the projectile to deviate from the original flight path.

53
Q

What is the definition of Magnus force?

A

Force created from high to low pressure gradients on opposing surfaces of a spinning projectile.

54
Q

What is the affect of the Magnus force?

A

Causes a spinning projectile to deviate away from its expected flight path

55
Q

What spin is from side views?

A

Topspin

Backspin

56
Q

What spin is from a top view?

A

Right side spin - slice

Left sidespin - hook

57
Q

Where is the eccentric force applied on each type of spin?

A

Topspin - above COM
Backspin - Below COM
Slice - Left of COM (spins right)
Hook - Right of COM (Spins left)

58
Q

What is the direction of spin/axis of rotation for topspin?

A

Spins downwards

Around transverse axis

59
Q

What is the direction of spin/axis of rotation for backspin?

A

Spins upwards

Around transverse axis

60
Q

What is the direction of spin/axis of rotation for a slice?

A

Spins right

Around longitudinal axis

61
Q

What is the direction of spin/axis of rotation for a hook?

A

Spins left

Around longitudinal axis

62
Q

What is the effect of topspin on flight path?

A

Shortens flight path

63
Q

What is the effect of backspin on flight path?

A

Lengthens flight path

64
Q

What is the effect of a slice on flight path?

A

Swerves to the right

65
Q

What is the effect of a hook on flight path?

A

Swerves to the left

66
Q

Describe the upper surface in a ball with topspin?

A

Rotates opposite to airflow, decreasing velocity to create a high pressure area

67
Q

Describe the lower surface in a ball with topspin?

A

Rotates in same direction as airflow, increases velocity creating an area of low pressure

68
Q

How does a ball with topspin create a Magnus force?

A

Creates an area of high/low pressure. Magnus force acts downwards

69
Q

What is the affect of the Magnus force in a ball with topspin?

A

Downwards force increases weight/effect of gravity so projectile dips in flight and reduces flight path/distance.

70
Q

What is the advantage of topspin?

A

Dips so can be hit with a greater velocity and it will remain in bounds.
Increases stability in flight.

71
Q

What is the checklist for drawing an airflow diagram?

A

State spin/angle of view
Draw DOM arrow
Draw direction of spin arrows
Draw airflow opposite to DOM (3 lines each side)
Label area of high/low velocity
Label area of low/high pressure
Draw Magnus force from COM (high-low pressure)
Link to affect - performance/flight path if appropriate

72
Q

What are the advantages of hitting a ball with backspin?

A

Increased friction on landing, decelerates and increases bounce height on landing

PE - Biomechanics (10 decks)

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