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Y13 A Level PE- Jones > Projectile Motion > Flashcards

Projectile Motion Flashcards

1
Q

Define Projectile Motion?

A

The movement of a body through the air following a curved flight path, under the force of gravity.

(the horizontal distance an object moves)

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2
Q

Define projectile?

A

A body that is launched into the air and subjected to weight and air resistance.

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3
Q

What takes place once a projectile is in the air?

A

=FOLLOWS A FLIGHT PATH
The flight path from start to finish shows the overall distance travelled, and the way in which gravity accelerates the projectile back to the ground.

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4
Q

Give examples of Projectiles?

A

Any time contact breaks with the ground= a projectile
Athletes: long jumper, high jumper, ski jumper

Body’s: shuttlecock, shot put, javelin, football

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5
Q

What four factors affect the horizontal distance that an object travels?

A

Have Some Angle Awesomeness

Height of Release
Speed/velocity of Release
Angle of Release
Aerodynamic factors (Bernoulli and Magnus)

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6
Q

How does HEIGHT affect the horizontal distance that an object travels?

A

As the HEIGHT of release increases, the HORIZONTAL DISPLACEMENT of the projectile also increases.

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7
Q

How does SPEED/ VELOCITY affect the horizontal distance travelled?

A

An increase in SPEED/ VELEOCITY increases the HORIZONTAL DISPLACEMENT that the projectile moves within its flight path.

eg: a shot-putter increases their speed/ velocity by spinning to increase horizontal distance.

(LINK- Newtons 2nd Law of Acceleration)

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8
Q

How does the ANGLE OF RELEASE affect the horizontal distance that an object travels?

A

The optimum angle of release varies within different sports depending on RELEASE AND LANDING heights.

If the release height and landing height are equal (long jump), 45degrees is the optimum, most effective angle of release.

If the release height is above the landing (shot put), less than 45degrees (such as 30- doesn’t achieve sufficient height=flatter)

If the release height is below the landing height (basketball shot), more than 45degrees (such as 60 or 75- reaches peak height quickly.)

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9
Q

What are the axis on a projectile graph?

A

Height against Distance Travelled

This gives a quick visual impression of the flight path and can indicate what affected the flight path.

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10
Q

What happens in a PARABOLIC flight path?

A

If WEIGHT is the dominant force and air resistance is less than weight= PARABOLIC

This means the flight path is UNIFORM, and SYMETRICAL about it’s highest point.

eg: a shot put- very high mass and travels at a low velocity
- relatively small frontal cross sectional area

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11
Q

What happens at a NON PARABOLIC fight path?

A

If AIR RESISTANCE is the dominant force and weight is less than= NON PARABOLIC.

The flight is UNUNIFORM and ASYMTRICAL about it’s highest point.

eg: badminton shuttle- relatively mass and travels at a high velocity
- relatively uneven surface increases air resistance

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12
Q

Define Parabolic flight path:

A

A flight path symmetrical about it’s highest point caused by the dominant weight force of a projectile.

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13
Q

Define Non-parabolic flight path?

A

A flight path that is asymmetrical about it’s highest point caused by the dominant force of air resistance on a projectile

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14
Q

Define parabola?

A

A uniform curve symmetrical about it’s highest point.

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15
Q

What do free body diagrams show?

A

Show all of the forces acting on a body at a particular instant of time.

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16
Q

What are the three main points/ phases of motion within a flight path?

A

START
MID-FLIGHT
END OF FLIGHT

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17
Q

What are the main things to remember when drawing free body diagrams?

A
  • Arrows originate from centre of mass
  • Weight acts DOWNWARDS
  • Air resistance OPPOSES direction of motion

If PARABOLIC- label W^AR
If NON-PARABOLIC- label AR^W

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18
Q

What is the purpose of a Parallelogram of Forces?

A

To consider ALL of the forces acting on a projectile in flight, allowing you to calculate resultant (net) force.

19
Q

What’s the main things to remember when drawing a parallelogram of forces?

A
  1. Draw a free body diagram showing AR and W
  2. Add “broken” parallel lines to AR and W to create the parallelogram
  3. Draw on the Resultant Force from COM to opposite corner
20
Q

How can you determine the dominant force from a parallelogram of forces?

A

If the resultant force arrow is closer to the weight arrow where they meet then weight is dominant= PARABOLIC

If the resultant force is closer to the air resistance arrow where they meet then air resistance is the dominant force= NON PARABOLIC

21
Q

What are some reasons as to why we get a non- parabolic flight path?

A

AR is greater than W

  • objects travelling at high speeds eg: golf balls= increased Air Resistance
  • objects that have a large cross sectional area eg: footballs
  • objects that don’t have a smooth surface eg: badminton shuttle.
22
Q

What principle does a ski-jumper apply when going through the air?

A

The Bernoulli Principle= LIFT
(18th century professor)

A ski jumper will adopt an aerofoil shape and use the Bernoulli principle of “lift” to increase the time they hang in the air
=extends flight path
=extends distance covered.

23
Q

How does the creation of an additional lift force take place within Bernoulli’s Principle?

A
  • Created by the formation of a pressure gradient on opposing surfaces of a projectile in flight
  • This results in Bernoulli’s conclusion that the higher the velocity of air flow the lower the pressure.
24
Q

What is the overall affect of an additional lift force (APPLY to question)

A

Increase the time the projectile hangs in the air, extending the flight path and therefore horizontal distance covered, allowing them to score more markss.

25
Q

What takes place around the aerofoil shape?

A

= CURVED UPPER SURFACE and flat underneath

-As the aerofoil moves through the air the air is forced to part= different velocities for air to meet at the same time around the object.

=affects pressure of air flow
=gradient of pressure forms

26
Q

Describe the pressures and velocities on the aerofoil shape?

A

Upper curve= High Velocity= Low pressure

Lower flat surface= Low Velocity= High pressure

=gases move from high to low
=lift

27
Q

Which four diagrams can be used to show Bernoulli’s principle?

A
  1. Air flow Diagram- air flow arrowheads opposed D.o.M
    Label velocity, pressure and lift force from C.o.M
  2. Free body Diagram- shows all three forces of Lift Force, Weight, Air Resistance
    Label D. o. M
  3. Resultant Force Diagram- shows the sum of all forces in a parallelogram
  4. Fight Path Diagram- shows how much horizontal distance a projectile travels.
28
Q

When showing Bernoulli’s principle in a Resultant Force Diagram what do you do with the vertical forces?

A

=WEIGHT AND LIFT FORCE

=Weight- lift force= the lift therefore reduces the force of weight and shows the overall affects of an aerofoil in flight.

29
Q

What happens when the aerofoil shape is flipped?

A

Under the Bernoulli principle, inverting the aerofoil shape will create an additional downwards force (instead of lift).

F1 and TRACK CYCLING= greater speed can be achieved when travelling around corners= greater grip through downwards force.

30
Q

How are F1 cars adopted to the inverted Bernoulli principle?

A

-Spoiler bars act as an inverted aerofoil, forcing air underneath it
= pressure gradient formed
=additional downwards force is created, increasing friction around corners

31
Q

How are Track Cyclists adapted to the inverted Bernoulli principle?

A

Adopt a flat back position to invert the aerofoil shape to a flat surface on top.

=draw in air and create a low pressure
=additional downwards force is created, increasing friction around corners

32
Q

Who created the Magnus force principle?

A

Henrich Magnus applied fluid mechanics to rotating projectiles in the early 19th century.

33
Q

Define the Magnus effect?

A

Creation of an additional Magnus force on a spinning projectile which deviates from the expected flight path.

The deviation of a projectile from it’s ORIGINAL FLIGHT PATH

34
Q

How is the Magnus force created?

A
  • A spinning projectile creates a boundary layer of air round itself
  • One side of the projectile makes contact with the surrounding passing airflow= low velocity and high pressure.
  • The other side has the boundary layer moving in the same direction= high velocity/ quicker air flow and lower pressure.

ALSO- applying an external force outside the C.O.M results in spin (Angular Motion)

35
Q

Topspin flight change/ flight path deviation?

A

Top spin= on TOP of the C.o.M

-eccentric force applied above C.o.M so projectile spins downwards around the transverse axis= shortened flight path.

36
Q

Backspin/ flight path deviation?

A

Back spin= Below the C.o.M (BB)

-Eccentric force applied below the C.o.M, projectile spins upwards around the transverse axis= lengthens flight path.

37
Q

Sidespin Hook/ flight path deviation?

A

Sidespin HOOK (RIGHT HOOK)= applied right of C.o.M

-eccentric force applied to the C.o.M , projectile spins right to left around the longitudinal axis.

38
Q

Side-spin Slice/ flight path deviation?

A

Sidespin SLICE= a SLICE of LEFTover cake

-eccentric force applied to the left of the C.o.M, projectile spins left to right around the longitudinal axis.

39
Q

Describe what happens during top spin in tennis?

A

=An eccentric force applied ABOVE the C.o.M= moving down

=the upper surface of the projectile rotates AGAINST oncoming airflow= DECREASED velocity and a HIGH PRESSURE ZONE

=the lower surface of the projectile rotates WITH oncoming airflow= INCREASED velocity and a LOW PRESSURE ZONE

=a downwards Magnus force created( high to low pressure conc. gradient created)

=the downwards Magnus force adds weight to the projectile= gravity increased, flight path reduced.

40
Q

Describe what happens during back spin in tennis?

A

=an eccentric force is applied BELOW the C.o.M= moving up

=The upper surface of the projectile is rotating with the airflow= INCREASES velocity= LOW PRESSURE ZONE

=The lower surface of the projectile is rotating AGAINST the oncoming airflow= DECREASED velocity of air flow= HIGH PRESSURE ZONE

=Creates a magnus force acting upwards (high to low conc. gradient)

=this Upwards Magnus force DETRACTS from the force of gravity, INCREASING the flight path and flight time= floats for longer.

41
Q

Evaluate “Topspin”?

A

The flightpath is SHORTENED

+ve
=confuse the opposition through shortening the flight path in tennis, bringing the opponent close to the net

=can hit the ball with more force whilst being able to keep it on the table/ in play in table tennis

-ve
=if done incorrectly= land short and loose a point in tennis if it doesn’t go over the net

=can decrease the horizontal distance of the flight path too much within a golf swing, causing a greater distance to get to the hole to be created.

42
Q

Evaluate “Backspin”?

A

Flight path is LENGTHENED

+ve
=adds a greater distance onto a “long drive” in golf, allowing the ball to reach where it needs to be

=allows a greater amount of time for a table tennis player to recover and plan their next move

-ve
=if played too high in the air will make it very easy for opponent to prepare for their next shot= more time available

=the ball may be sent too far over the heads of the opponent and out of court in tennis singles, meaning the performer looses a point.

43
Q

Evaluate “Side spin”?

A

The projectile/ flightpath moves from left to right

+ve
=you can curve the ball in a football free kick to avoid obstructions and land in the goal

-ve
=it could curve too much and fall out of the goal as it’s a very HARD and COMPLEX skill to achieve

Y13 A Level PE- Jones (8 decks)

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