11.3 Projectile Motion

Question 1

What is projectile motion?

Answer 1

• Refers to the movement of either an object or the human body as they travel through the air

In sport as soon as a ball is released from a kick/throw it becomes projectile
The body becomes a projectile as soon as it is thrown into the air e.g. a somersault

Question 2

What is horizontal displacement?

Answer 2

• The shortest distance from the starting point to the finishing point in a line parrallel to the ground

Question 3

What are the factors affecting the horizontal displacement of a projectile?

Answer 3

• Angle of release
• Speed of release
  Height of release

Question 4

What is the optimal angle of release?

Answer 4

• This optimal angle of release is dependant upon release height & landing height
• It is the angle between the horizontal & the direction of projectile at release

Question 5

What happens when both the release height & landing height are equal?

Answer 5

When both the release height & landing height are equal, then the optimal aqngle of release is 45 degrees (ignoring wind resistance & gravity)

Question 6

What happens when both the release height is below the landing height?

Answer 6

• Then the optimum angle of release needs to be greater than 45 degrees
• e.g. shooting in basket ball

Question 7

What happens when the release height is greater than the landing height?

Answer 7

• If release height is greater than landing height the optimum angle of release needs to be less than 45 degrees

e.g. this can be seen in the flight path of a shotput where the hand is the point of the release which is much higher than the landing point

Question 8

What is the optimum angle of release for a professional shot putter?

Answer 8

• Anywhere between 26 to 38 degrees
• Keeping the release angle smaller means more speed can be generated as the shot is released
• The optimum angle of release for a shot putter will also depend on the size, strength & throwing technique of the athlete

Question 9

What is the speed of release?

Answer 9

• The greater the release velocity of a projectile, the greater the horizontal displacement travelled
• e.g. in the shot put, the speed of the shift or rotation across the circle ensures that the shot leaves the hand at maximum velocity so a greater horizontal displacement can be achieved.

Question 10

What is the height of release?

Answer 10

• A greater height of release also results in an increase in horizontal displacement
• The force of gravity is constantly acting on the mass of a shotput
• This therefore means that technically the shot putter should try to release the shot at the highest point possible above the groun to gain maximum horizontal displacement/

e.g. when feilding a ball in cricket the taller the fielder the further horizontal displacement, providing the angle of release & velocity of the release are the same
In order for a smaller fielder to achieve the same displacement, they will have to manipulate both their angle & velocity of release

Question 11

What are the factors affecting flight paths of different?

Answer 11

• Weight (gravity) and air resistance are two forces that affect projectiles while they are in the air
• These two factors are crucial in deciding whether a projectile has flight path that is a true parabola or a distorted parabola

Question 12

What is a parabola?

Answer 12

• A curve with matching left & right hand sides

Question 13

What do projectiles with a large weight force do?

Answer 13

• Projectiles with a large weight force have a small air resistance force & follow a true parabolic flight path
  e.g. a shot put

Question 14

What do projectiles with a lighter force do?

Answer 14

• Projectiles with a lighter mass, the effects of air resistance result in a flight path that deviates from a true parabola to a distorted parabola
  e.g. a badminton shuttlecock