Sports Medicine Final Sem 2

Forces & Biomechanics Test w/ IB SL

Line of Gravity?

The imaginary vertical line running through the center of mass towards the ground

Newton’s 3 Laws of Motion

1. An object in motion stays in motion, and an object at rest stays at rest UNLESS a force is applied

2. Force equals mass times acceleration

3. For every action, there is an equal but opposite reaction

What is the difference between inertia and momentum?

Inertia = tendency to resist a change in motion

Momentum = moving inertia that makes something hard to stop

What is IMPULSE?

Change in momentum

Impulse - momentum equation

f x t = change in mass x velocity

Why do athletes avoid injury by bending their knees after jumping?

Increases the time (bigger change in momentum) and decreases force

How do you move your center of mass?

By moving your body limbs

How does an athlete stay balanced/ stable? (Relating to center of mass + base of support)

By keeping their center of mass directly above their base of support

What does a position-time graph look like during acceleration?

A curve

What is the relationship between initial speed and range of a projectile?

The initial speed increases the range of the projectile

When you double the initial speed, do you double the range each time?

No its a squared relationship

What is the relationship between height off the ground and range of a projectile?

The higher off the ground, the higher the range of projectile

When you double the initial height, do you double the range?

No, it doesn’t increase by alot

What angle makes a projectile go farthest?

45 degrees

What is the relationship between mass and projectile?

TRICK Q: Mass does not affect the range of a projectile

When there is air resistance for object w/ more mass, does the range of a projectile change?

Not really, air resistance wouldn’t affect objects with a heavier mass as much. It also depends on shape and size, there isn’t an overall pattern.

3 things that affect a projectile that has the biggest effect to to the smallest effect

Initial speed, 45, initial height

What are the only forces acting on an object once its in the air?

Gravity and air resistance

What shape or path a projectile take?

Parabola

Does gravity affect vertical velocity or horizontal velocity?

Gravity only affects VERTICAL not horizontal

What is the extra characteristic angular momentum has that linear motion doesn’t?

Distance from axis

What is angular momentum?

Describes why spinning object is hard to stop

Angular momentum EQUATION

Moment of inertia (Distance from axis)(mass) X Angular velocity

What does the LAW OF CONSERVATION say?

Momentum stays the same even if an object moves UNLESS forces act on the system

When you bring your arms in - What happens to the moment of inertia, angular velocity, and angular momentum?

Moi = decreases

Velocity = increases

Angular momentum = Doesn’t change

When you bring your arms out - What happens to the moment of inertia, angular velocity, and angular momentum?

Moi = Increases

Velocity = Decreases

Angular momentum =

Is it correct to say that a cart with a lot of mass has less speed? Why or why not?

NO, that cart just requires more force to get basic to the same speed

Do force and mass act the same way on the acceleration of an object? Explain.

No, they are opposite. More force increases acceleration and more mass decreases acceleration

What do forces cause_____ The stronger the force, the _____the acceleration

1. Acceleration

2. Higher

What is instantaneous velocity?

Velocity in one moment of time

Acceleration EQUATION

v2-v1/ t

Speed/ Velocity EQUATION

distance over time or d/t

Displacement/ distance unit

Velocity unit

Acceleration unit

M = meter

m/s = meters per seconds

m/s2 = meters per seconds squared

What are the VECTOR measurements?

Displacement

Velocity

Acceleration

What are the SCALAR measurements?

Distance and speed

What is the DIFFERENCE between scalar and vector?

A vector HAS a direction, a scalar DOESNT.

What do both follow-through and recovery reduce? What is different?

1. Both reduce injury

2. Follow-through increases accuracy / recovery maintains momentum

What are 2 reasons movement analysis is used?

1. Prevent injuries

2. Improve performance

Which movement phase would reveal that an athlete needs to practice their TIMING & TECHNIQUE?

Critical instant

Which movement phase would reveal that an athlete needs to REDUCE ANXIETY and focus more?

Preparatory

Which movement phase would reveal MISALIGNMENT of a joint?

Follow-through

Which movement phase(s) reveal someone’s POOR BALANCE?

Preparatory

Which movement phase(s) reveal MUSCLE WEAKNESS?

Force production and preparatory

What are the 4 phases of movement?

1. Preparatory

2. Force Production

3. Critical Instant

4. Follow-Through

Examples of discrete and continuous skills

Discrete = Throwing a ball, jumping

Continuous = Running, cycling, swimming

What is the difference between discrete and continuous skills?

Discrete = have clear beginning/end, and usually last a short time

Continuous = have no clear beginning/end - repeat over and over and last a long time

The higher the mass the_____ it is to accelerate quickly

Harder

Momentum unit

Forces unit

Impulse unit

kg m/s = kilograms meter per seconds

N = newtons

Nxs = newtons seconds

Which object is slowed down more by air resistance? Slow-moving objects or fast-moving objects? Why?

Fast, because air resistance is higher = more air resistance causes a faster DECCELERATION

Which object is slowed down more by air resistance? Light objects or heavy objects? Why?

Light objects increase the effect of air resistance. Air resistance wouldn’t affect heavy objects as much.

What are the MAIN focuses of each movement?

Preparatory = Body position, balance, and the goal

FP = Coordinating skeletal and muscular system

CI = Timing of movement when contact is made/lost

F-T = maintaining correct alignment

What are the types of forces? (6)

Normal force = F norm

Applied force = F app

Gravitational force = F grav

Friction force = F frict

Air resistance force = F air

Tension force = F tens

Scalar (vocab)

A quantity that has only magnitude

Vector (vocab)

A quantity that has magnitude and a direction

Impulse (vocab)

Force multiplied by the time; or change in momentum

Force (vocab)

A push or a pull

Distance (vocab)

How much ground an object covers while moving

Displacement (vocab)

The overall change in position of a moving object

Base of Support (vocab)

The area between all points of contact with the ground

Acceleration (vocab)

Change in velocity over time

Center of Mass (vocab)

The average position of all an object’s mass

Momentum (vocab)

The mass times the change in velocity; or the impulse

Velocity (vocab)

CHANGE in distance over time in a DIRECTION

Projectile (vocab)

An object flying through the air that only experiences the force of gravity