Unit 4.3

Question 1

Scalar definition

Answer 1

a measurement that only has size (ex. 5m)

Question 2

Vector definition

Answer 2

• a measurement that has both size and direction (ex. 5m west)

Question 3

Force definition and equation + unit

Answer 3

• the mechanical interaction that goes on between 2 objects

mass x acceleration (N)

Question 4

Speed definition and equation + unit

Answer 4

• the rate at which someone or something is able to move or operate

distance/time (m/s)

Question 5

Velocity definition and equation + unit

Answer 5

• the speed of something in a given direction

displacement change/time (m/s)

Question 6

Displacement definition

Answer 6

how far an object has moved horizontally, vertically or laterally

Question 7

Acceleration definition and equation + unit

Answer 7

the increase in rate of speed

change in velocity/time (m/s²)

Question 8

Momentum definition and equation + unit

Answer 8

• the measure of the amount of motion possessed by a moving body

mass of object x velocity (kgm/s)

Question 9

Impulse equation +unit

Answer 9

force x time (N/s)

Question 10

Velocity-Time Graph:

Answer 10

positive gradient line vertical: constant acceleration

horizontal line : constant velocity (no change in speed)

and negative gradient: constant deceleration

Question 11

Distance time graph, describe lines

Answer 11

if positive gradient straight line vertical: fast steady speed

horizontal line: no movement (stop)

negative gradient straight line: steady speed return to start position

Arched line up: acceleration

Question 12

Explain Force time Graph using sprinter

Answer 12

Beggining:
Larger positive impulse as the performer is accelerating (greater velocity)

Middle of race:
runner is at a constant velocity
the landing of feet causes negative impulse and push off creates positive impulse. This means they are equal in area size.

End of race:

Net impulse is negative as performer is decelerating, meaning greater negative impulse.

Question 13

Center of mass

Answer 13

• the mathematical point around which the mass of a body or object is evenly
  distributed

-Depends on the distribution of the material in a body or object

• Men tend to have a higher center of mass, due to broad shoulders
• Women tend to have a lower center of mass, due to wider hips
• It is not always inside the body, it can be outside of the body depending on the position

Question 14

Named example of where shifting center of mass is good

Answer 14

Fosbury Flop in high jump:
The center of mass in this jump is externally placed
- the arch in the back allows the mass to be shifted to the outside of the body, and there is a
greater opportunity for clearance
- the greater the arch of the back the lower the center of mass is

Question 15

Distinguish between first, second and third-class levers

Answer 15

First: fulcrum in middle
(common example, header)
Second: load in middle
(calf raises)
Third: effort in middle
(dumbel)

Question 16

Label the anatomical representation of levers

Answer 16

Lever - bone
Fulcrum - the joint
Load - the force applied to the muscle (body weight or dumbbell)
Effort - the muscle that moves the force

Question 17

Lenghts of levers

Answer 17

The longer the length of the resistance arm of the lever, the greater the speed will be at the end of it. This means that in some sports, taller people, with long arms are at an advantage.

Question 18

Mechanical disadvantage

Answer 18

1.Overcome large loads with little effort

2.Very long effort arm (distance between the effort to fulcrum)

3.Short resistance arm/load arm (distance between load and fulcrum)

4. Short range of motion

mechanical disadvantage occurs when the load arm (resistance arm) is shorter than the effort arm (force arm)

Question 18

Mechanical advantage

Answer 18

1) produce a wide range of movement or fast movement

2)long resistance arm(distance between the load to fulcrum)

3)some of class 1 and all of class 3 are always a mechanical disadvantage

4) can’t overcome large loads

Note: The longer the resistance arm, the greater speed can be generated.

Question 19

Newton’s 1st law

Answer 19

A body stays in its state of rest or continues with a constant velocity, unless acted on by an external unbalanced force

ex free kick football, the ball is stationary unless football kicks it

Question 20

Newtons second Law

Answer 20

The acceleration of a body is proportional to, and in the same direction of, the unbalanced force applied to it

Force = Mass x Acceleration

ex. If the same forces are applied, a heavy object like a shot put will accelerate less when compared with a lighter object like a table tennis ball. Therefore, to accelerate heavier objects, heavier forces are needed.

Question 21

newtons third law

Answer 21

When one body applies a force to another, the second body will apply a force equal in size but in the opposite direction

OR “For every action there is and equal and opposite reaction”.

ex. When a swimmer pushes off the side of the pool, she exerts a force onto the wall. The wall exerts the same force but in the opposite direction. The wall has a much larger mass, and does not move (technically it does), but the swimmer will accelerate

Question 22

Angular Momentum definition and equation

Answer 22

the amount of rotation of a body

Angular Momentum = Angular Velocity x Moment of Inertia

Question 23

Moment of Inertia

Answer 23

The force needed for an object to rotate

↳ It depends on the mass and shape of the object

The further from the axis of rotation the mass is located, the larger the moment of inertia which decreases angular momentum

Question 24

Angular Velocity

Answer 24

a measure of how fast an object is rotating

Question 25

When a ice skater has arms out explain relashionship between angular momentum moment of inertia and angular velocity

Answer 25

Opened arms means there is a high moment of inertia, making the angular velocity decrease and causing the figure skater to slow down

There is an inverse relationship between the moment of inertia and angular velocity

Question 26

Explain the concept of angular momentum in relation to sporting activities
(front flip)

Answer 26

• After take off the gymnast moves into a tucked position, decreasing the moment of inertia
• Moving from a stretched position to a tucked position, increases angular velocity, as the body rotates faster
• As she comes out from the tucked position, she extends her body for the landing, the moment of inertia increases, and the angular velocity slows down

Question 27

Explain the factors that affect projectile motion at take-off or release

Answer 27

Height of Release If it is high:
- More distance covered
- More time spent in the air

Angle of Release: Ideal angle is 45°

Speed of Release: Directly related to the distance

Question 28

Bernoulli’s Principle

Answer 28

When an object moves through a liquid, the pressure it exerts reduces as its velocity increases

Part where there is faster moving air=Less pressure

Part where there is slow moving air=more pressure

Air moves from high to low pressure causing lift

Question 29

Magnus effect

Answer 29

Magnus effect is a particular manifestation of Bernoulli’s theorem: fluid pressure decreases at points where the speed of the fluid increases. In the case of a ball spinning through the air, the turning ball drags some of the air around with it.

ex. adding spin to a ball

Backspin: The ball, moving from right to left is spinning with back spin.

Air travelling over the top of the ball is moving faster than air on the bottom.

This creates low pressure at the top of the ball and the ball will move towards this.

Therefore, a golf ball hit with back spin will lift, staying in the air longer and bouncing less when hitting the ground

Same concept for topspin.