Understanding Force and Torque

• Force is a push or pull that causes movement or changes an object's motion.
• Force equals mass times acceleration (FMA).
• Force also equals weight times the rate of change in velocity.
• Mass is usually constant, so a larger force results in increased acceleration.

Types of Forces

• Applied force is exerted from one object to another.
• Gravitational force pulls objects toward Earth at 9.8 m/s².
• Frictional force occurs when two surfaces contact each other.
• Some sports modify friction by increasing it (using chalk in gymnastics) or decreasing it (skiing).

Torque

• Torque occurs when an eccentric force causes an object to rotate.
• It creates angular motion, which is rotation around a central axis, typically a joint in the body.
• Eccentric force is applied away from an object's center of gravity, causing rotation and forward movement.
• Torque equals force times lever arm (TFL).
• Torque is the amount of force applied multiplied by the distance from the axis.
• Lever arm is the distance from an object's center of gravity.
• A bigger lever arm allows force application over a longer distance, increasing torque and angular motion.

Linear Momentum

• Linear Momentum involves the amount of motion an object has and its resistance to changes in that motion.
• Momentum equals mass times velocity.
• A non-moving object has zero momentum because its velocity is zero.
• Objects with greater momentum are harder to stop.

Conservation of Momentum

• The total momentum before a collision is equal to the total momentum after the collision.

Angular Momentum

• Angular momentum is the amount of rotation an object has around an object.
• Angular momentum equals moment of inertia times angular velocity.
• Moment of inertia is an object's resistance to rotation.
• Decreasing moment of inertia (MOI) increases angular velocity.

Conservation of Angular Momentum

• Angular momentum is conserved when the body is in flight and does not change.
• Mass closer to the axis increases angular velocity.
• Changing MOI allows manipulation of angular velocity.

Impulse

• Impulse represents an object's change in momentum.
• Objects can speed up through positive acceleration or slow down through negative acceleration.
• Impulse equals force times time.
• Impulse can be increased by extending the time the force is applied, such as following through when throwing.
• Impulse can be manipulated to slow down an object's momentum, like extending catching time.

Summation of Momentum

• Sequential movement of multiple body parts produces maximum velocity.
• This happens at the point of contact or release.
• A greater summation of momentum is needed to throw an object as far as possible.
• More body parts lead to greater summation of momentum.
• The sequence goes from larger, slower moving parts to smaller, faster moving parts.
• Each body part stabilizes before momentum transfers to the next.
• Velocity should continue after release or contact; a 'follow-through' is needed.

Linear Motion

• Linear motion is the movement of the body along a straight or curved path.
• All body parts move in the same direction and at the same speed.

Distance

• Speed is the rate of motion of an object.
• Speed describes how fast an object is traveling.
• Speed equals distance divided by time.

Displacement

• Velocity also describes the rate of motion.
• Velocity is measured in a specific direction.
• Velocity equals displacement divided by time.

Linear Acceleration

• Linear acceleration involves changes in velocity over a period of time.
• Acceleration can be positive or negative.
• Acceleration is measured in meters per second squared (m/s²).
• Acceleration equals the change in velocity divided by the change in time.
• Zero acceleration does not mean the object has stopped, it means it is no longer speeding up or slowing down, this is constant velocity.

Angular Speed and Velocity

• Angular Speed equals angular distance divided by time (degrees/second).
• Angular Velocity equals angular displacement divided by time.
• Linear and angular velocity relate to hitting, kicking, or throwing an object.
• They are related when trying to achieve maximum linear velocity.
• Linear Velocity equals the radius of rotation times angular velocity.
• When hitting a ball, an increased radius of rotation (longer bat) will increase the ball's linear velocity.
• If the bat is too heavy, angular velocity is compromised, decreasing the distance of the hit.

Angular Acceleration

• Angular acceleration measures the rate of change of angular velocity.
• It indicates how quickly the body changes its angular position.
• It can be positive, negative, or zero.
• Measured in degrees per second squared.

Law of Inertia

• A body remains at rest or in uniform motion in a straight line unless acted upon by an external force.
• A tennis ball will continue traveling in the serve's direction until the opponent applies a force and hits it back.

Inertia

• Inertia is the tendency of a body to resist changes in its state of motion, whether resting or moving.
• Inertia is directly related to mass.
• Greater mass means greater inertia, it requires more force to change the state of motion.
• If the force applied to an object is not greater than its inertia, its motion will be unchanged.

Law of Acceleration

• A force applied to an object produces a change in motion (acceleration).
• The force direction is directly proportional to the size of the force.
• Playing in wet conditions the ball is waterlogged, heavier, increased mass, so increased force is required to kick even the same distance.
• Acceleration is the rate of change in an object's velocity.
• Greater force leads to greater acceleration as greater mass leads to less acceleration.
• Force equals mass times acceleration.

Law of Action-Reaction

• For every action, there is an equal and opposite reaction.
• The faster a tennis racquet is moved before ball contact, the greater the generated force, which affects the ball.
• Any movement of an airborne object is only affected by gravity and air resistance.

Height of Release

• Height of release is the difference between the height a projectile is released from and the height at which it lands or stops.
• For any body serving as the projectile, the body's center of mass determine release height, not the ground.
• With a netball player releasing a ball at 2.2 m, the height of release is 2.2 m.
• A soccer player kicking a ball, the height of release is 0 m.

Speed of Release

• The speed at which an object is thrown, kicked, or propelled into the air.
• Has both vertical and horizontal components.
• Determines the height reached and flight time of the projectile.

Angle of Release

• The angle (with respect to horizontal) at which an object is projected into the air.
• Determines the flight path.

Flight Path

• Vertical direction during a vertical jump in volleyball.
• Parabolic direction between 0 and 90 degrees in javelin.
• Half a parabolic direction at 0 degrees in lawn bowls.

Furthest Distance

• The angle producing the furthest distance is 45 degrees only when the height of release and landing height are the same, like in a softball pitch.
• Height of release higher than landing height requires an under 45 degrees, like in a javelin or shot put.
• Height of release is lower than landing height requires an over 45 degrees, like in a high jump.

Equilibrium

• Equilibrium is the state of motion in which the forces and torques are balanced.
• Net force is balanced equaling zero or a net constant velocity.

Balance

• Balance is the ability to control equilibrium whilst both at rest or moving.

Stability

• Stability is the ability to resist changes in a body's equilibrium.
• The ability to maintain equilibrium is affected by base of support, centre of gravity, body mass, line of gravity and friction.

Base of Support

• Base of support is the area bounded by the outside edges of the body parts that are in contact with the floor or other surfaces.
• A larger base of support gives greater stability and uses a decreasing degree of muscular effort of body.

Center of Gravity

• The point around which a body's weight is balanced, regardless of the body's position.
• Generally located at our navel but moving a body part will change it.
• Stability is increased when the center of gravity is lowered provided that gravity falls within the base of support.
• An individual is more stable when crouched down low than on tippy toes.

Line of Gravity

• The line of gravity is an imaginary line that passes through the center of gravity in the direction that gravity acts.
• When the line of gravity acts through the center of the base of support, stability is increased.
• Stability is disrupted when the line moves outside or towards the edge of the base of support.
• Sprinters position themselves on the block so their line of gravity is towards the front of their base of support.
• The athlete is less stable and easily accelerates forward from the blocks, results in improved performance.

Levers

• The human body is made up of levers (anatomical).
• All levers are made up of three parts, the axis, resistance arm and the force.
• Axis defined as the pivot point.
• Resistance arm defined as the weight or load.
• Force is the effort.
• The shoulder joint is the axis, the club head is the resistance and muscles in the arms is the force acting on a golf ball swing.

Levers - 3rd Class

• Resistance is always at the end of third class levers.
• The mechanical advantage is always less than 1.
• They are designed for greater range of motion and speed.
• It takes larger force to move any lever.

Mechanical Advantage

• The ratio of the force arm to the resistance arm.
• Mechanical advantage equals force arm divided by resistance arm.
• Levers with a longer force arm than resistance have MA values greater than 1 and can lift heavy loads.
• 3rd class levers have a longer resistance arm and decreased force arm with a less than 1 value.
• A greater force is required in order to move the resistance but you will not get greater range of motion and speed.
• Athletes will be able to improve performance with a longer lever, which creates greater velocity; assuming you can apply greater muscular force.
• Younger athletes will not improve performance due to the larger force required to overcome inertia.

Qualitative Movement Analysis

• A non-numerical collection, evaluation, and analysis of a movement skill or sequence.

Stages of Qualitative Movement Analysis

• Preparation stage - comes up with the best plan to get best improvement. Includes
• What are the critical features of this skill when performed at the highest level?
• Current learning stage and skill stage of an athlete?
• What observation method is going to be used?
• Observation stage is the direction observation and note taking of the skill. This includes
• Where is it viewed such as at training or competition?
• Distance for viewing (avoid interference)
• Viewing angle eg: front or back
• Photos/videos
• Viewing skill many times increases the reliability during this stage
• Evaluation stage that involves objective or subjective opinions
• Compare performance with elite athletes
• Determine strengths and weaknesses
• What is causing these weaknesses? How can they be improved?
• Error correction stage
• How are skills best learnt and practiced? Direct or constraint coaching?
• What is a more relevant and effective form of feedback? Intrinsic or augmented? (knowledge of performance)
• What is the best time to make an intervention? Training or in games?
• Offer demonstrations including breaking down the movement into subroutines