Biomechanics: Projectile motion

Question 1

Define projectile motion

Answer 1

• The motion of an object being projected into the air at an angle.

Question 2

What are the 3 factors the determine the horizontal displacement of a projectile?

Answer 2

1. Velocity of release.
   - The greater the velocity of a object the further it will go.
2. Height of release.
   - The greater the height of release of an object the further it will go.
3. Angle of release.
   - There is always an ‘optimal’ angle for release.

Question 3

What should be considered during the angle of release?

Answer 3

1. Height of release.
2. Landing height.

Question 4

Long jump

Answer 4

• Height of release= landing height.
• Optimal angle= 45 degrees.

Question 5

Shotput

Answer 5

• Release height > Landing height.
• Optimal angle= less than 45 degrees.

Question 6

Free throw

Answer 6

• Release height < Landing height.
• Optimal angle of release= greater than 45 degrees.

Question 7

Flight paths

Answer 7

• A projectile can either have a parabolic (symmetrical) flight path or a distorted parabolic (asymmetrical) flight path.

Question 8

What are the 2 main forces that affect projectiles?

Answer 8

• Weight (W)- Vertical force.
• Air resistance (AR)- Horizontal force.

Question 9

Air resistance

Answer 9

• If AR is low and has little effect on the momentum of an object, the object will have a parabolic flight path.
  *Objects with a large weight have small AR.
• If AR is high it will have a subsequent effect on the momentum of the object therefore it will have a distorted parabolic flight path.

Question 10

Flight path of a shotput

Answer 10

• The speed of a shotput is relatively slow and the weight is large, therefore we do not need to consider AR.
• Momentum will be constant.
• Therefore the flight path of a shotput will be parabolic.

Question 11

Flight path of a shotput (pt.2)

Answer 11

• Angle of release must be less than 45 degrees due to the height of release. Elite shot-putters tend to release around 34 degrees.
• Positive vertical components (action force) quickly turn into negative vertical components due to gravity.
• Gravity plays a large role in determining distance.
• Velocity of release is the key to distance, as the steeper the angle of release the slower the velocity.

Question 12

Shot put flight path including horizontal and vertical components

Answer 12

1. Horizontal force (momentum) stays the same throughout flight in all FOUR areas- release point, highest point, opposite angle of release, point before contact.
2. Highest point only has this horizontal force drawn.
3. Size downward arrow (w) opposite release point should be equal to vertical force.
4. Downward arrow (w) should be longer at point of contact than previous downwards arrow.

Question 13

Look at drawn flight path of a shotput!!!!