Unit 4.3 Flashcards
Scalar definition
a measurement that only has size (ex. 5m)
Vector definition
- a measurement that has both size and direction (ex. 5m west)
Force definition and equation + unit
- the mechanical interaction that goes on between 2 objects
mass x acceleration (N)
Speed definition and equation + unit
- the rate at which someone or something is able to move or operate
distance/time (m/s)
Velocity definition and equation + unit
- the speed of something in a given direction
displacement change/time (m/s)
Displacement definition
how far an object has moved horizontally, vertically or laterally
Acceleration definition and equation + unit
the increase in rate of speed
change in velocity/time (m/s²)
Momentum definition and equation + unit
- the measure of the amount of motion possessed by a moving body
mass of object x velocity (kgm/s)
Impulse equation +unit
force x time (N/s)
Velocity-Time Graph:
positive gradient line vertical: constant acceleration
horizontal line : constant velocity (no change in speed)
and negative gradient: constant deceleration
Distance time graph, describe lines
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
Explain Force time Graph using sprinter
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.
Center of mass
- 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
Named example of where shifting center of mass is good
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
Distinguish between first, second and third-class levers
First: fulcrum in middle
(common example, header)
Second: load in middle
(calf raises)
Third: effort in middle
(dumbel)
Label the anatomical representation of levers
Lever - bone
Fulcrum - the joint
Load - the force applied to the muscle (body weight or dumbbell)
Effort - the muscle that moves the force
Lenghts of levers
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.
Mechanical disadvantage
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)
- Short range of motion
mechanical disadvantage occurs when the load arm (resistance arm) is shorter than the effort arm (force arm)
Mechanical advantage
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.
Newton’s 1st law
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
Newtons second Law
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.
newtons third law
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
Angular Momentum definition and equation
the amount of rotation of a body
Angular Momentum = Angular Velocity x Moment of Inertia
Moment of Inertia
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
Angular Velocity
a measure of how fast an object is rotating
When a ice skater has arms out explain relashionship between angular momentum moment of inertia and angular velocity
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
Explain the concept of angular momentum in relation to sporting activities
(front flip)
- 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
Explain the factors that affect projectile motion at take-off or release
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
Bernoulli’s Principle
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
Magnus effect
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.
