Levers, Newton's Laws, Kinematics and Kinetics

sports science HL

First class lever

First class lever

Resistance——Fulcrum——Effort

Second class lever

Fulcrum——Resistance——Effort

Third class lever

Fulcrum——Effort——Resistance

mechanical advantage

class 2 lever. when effort arm>resistance arm, it gives more power

mechanical disadvantage

Class 3 lever. when effort arm<resistance arm, it gives more speed but is harder to move

Newton’s first law

Law of inertia. an object will remain at rest or continue with constant velocity unless acted on by an unbalanced force

Newton’s second law

Law of acceleration. Force= mass×acceleration

Newton’s third law

Law of reaction. For every action there is an equal and opposite reaction force applied.

inertia

a property of matter that causes it to resist changes in velocity (speed/direction)

Center of Mass (CoM)

mathematical point around which the mass of a body is evenly distributed.

CoM and stability

the CoM must be in the Base of Support (BoS)to have balance. The lower the CoM the more stable the object is

Summation of Forces

Normally the strongest and lowest body parts around the center of gravity move first, followed by the weaker, faster, and lighter extremities. The order reflects the best techniques.

Kinematics

study of motion

Kinetics

study of forces that cause motion

Scalor

size

Vector

size+direction

displacement

The distance from the starting point. Has size+direction

distance

has only size but no direction

angular kinematics

movement around an axis (spinning)

momentum

The force of a moving object. measured in newtons. p=mv

Impulse

force applied in a certain timeframe. I=Ft

Impulse momentum principle

total momentum before impact =total momentum after impact

moment

a force that is rotational (spins around CoM)

Angular momentum

the force of rotation and is based on the moment of inertia and angular velocity

moment of inertia

the property of an object to resist spinning, or to resist not spinning. the more mass an object has the harder it is to start spinning, the harder it is to stop spinning

factors affecting the amount of spinning

1. size of the applied force

2. direction of the applied force

3. how far from the axis of rotation the force is applied

the conservation of angular momentum

when an object is freely rotating (in the air), the amount of angular momentum is conserved. If the moment of inertia changes, the angular velocity will be affected.

conservation of momentum

the total momentum of a closed system remains constant, provided no external forces are acting on it

coefficient of restitution

a measure of how elastic a collision is between two objects, between 0 and 1

work

W=Fs, forced applied on an objects and the resulting displacement

Power

The measure of how much Work is being done, measured in Watts (J/s)

Kenetic energy

the energy of an object in motion

Potential energy

stored energy an object has due to its position/state

chemical energy

energy stored in bonds between atoms and moleules.