W4 Projectile Motion

Question 1

What is the effect of increasing the vertical velocity of an object?

Answer 1

1. Larger overall height
2. Greater flight time
3. Greater range

Question 2

What is the effect of increasing the horizontal velocity of an object?

Answer 2

1. Greater range
   
   • The same flight time
   • The same height

Question 3

What’s the definition of a Vector?

Answer 3

An arrow in two dimensions that describes some kind of physical quantity.
In layman’s terms: A vector is something with both magnitude and direction
E.g. Velocity or Force (in a specific direction)

Question 4

What is Kinetics?

Answer 4

• The study of forces (external & internal) causing motion.

Question 5

What’s the definition of inertia?

Answer 5

• An ability to remain unchanged or resist movement

Question 6

What is Newton’s Law of Gravity?

Answer 6

• The greater the masses of two objects the greater the attraction between them.
• Also, the greater the distance between two objects the less attraction.

Question 7

What’s the definition of weight?

Answer 7

The attractive force (gravity) that the Earth exerts on a body/object.

Question 8

Newton’s Law of Gravity:

• Would a person weight change depending on where they stood on the planet?
• If so, why?
• What about a persons mass?

Answer 8

• Weight does change
• Because the Earth is flatter at the North & South Pole. So the distance between them and the centre of Earth is less than someone stood in Kenya.
• A persons mass remains the same

Question 9

What is Newton’s 1st Law of Motion?

Answer 9

• Everything continues in a state of rest or uniform motion unless compelled to change by an external force.
• Either stationary object beginning to move or increasing somethings acceleration.

Question 10

What is Newton’s 2nd Law of Motion?

Answer 10

• The acceleration of an object is proportional to the force causing it.

Question 11

What is Newton’s 3rd Law of Motion?

Answer 11

• For every force exerted on an object their is an equal and opposite reaction force.

Question 12

What tool/instrument do we use to measure internal forces?

Answer 12

• A force plate

Question 13

Ground Reaction Force (GRF): Vertical GRF has two peak forces during a rear foot strike in running.
What are they two peak forces and where do they happen on the graph?

Answer 13

1. Peak Impact Force
2. Peak Active Force
   - The Peak Impact Force happens first (on the small peak) and the Peak Active Force happens second (on the bigger peak).

Question 14

Ground Reaction Force (GRF): Horizontal GRF (Anterior –> Posterior) has two peak forces during a rear foot strike in running (the graph looks like a sideways ‘S’).
What are they two peak forces and where do they happen on the graph?

Answer 14

1. Peak Breaking Force
2. Peak Propulsive Force
   - Peak Breaking Force (the minus number) happens first followed by the Peak Propulsive Force (the positive number).

Question 15

Name factors that influence GRF.

Answer 15

• Speed (magnitude & contact time)
• Mass (normally greater mass = greater magnitude)
  Sometimes effects:
• Surface area
• Footwear
• Giat Kinematics (the way someone walks)