Week 2: Kinetics Flashcards
What is the term for the displacement of a body or one of it’s segments from one point to another?
Motion
Linear motion is also known as what type of motion?
Translational Motion
Movement around an axis is known as this type of motion?
Rotational Motion
Movement around joints is usually what kind of motion?
Rotational
True or False: Movement is a combination of rotational and translational?
True
Linear or Translational Motion is measured in what?
Meters AND/OR feet per second
Rotational Motion is measured in what?
Degrees (for ROM) per second
What is the term for the distance that a force moves a body?
Magnitude
True or False: Direction of motion cannot be positive and negative
False
What is the term for the rate at which the body or segments move?
Velocity
What is the term for a push or pull that produces displacement?
Force
What is the term for the motion of a body or segment that occurs when force is applied?
Displacement
What is the term for when a system is in balance?
Equilibrium
What is the term for the amount of matter contained within an object?
Mass
True or False: Mass is a variable amount
False, it is constant
What is the term for the force of gravity on an object which changes depending on gravitational pull?
Weight
What is the term for the elements that produce force on bone segments by active contraction and passive stretching?
Muscles
Four primary forces?
- Gravity
- Muscles
- Externally Applied Resistance
- Friction
What is the result of force acting at a distance from the point of motion or the axis
Moment
What is the moment equation?
Moment = distance x force
What is the force equation?
Force = mass of an object x acceleration of an object
2 elements that help express “force”?
- Magnitude
2. Rate of change
Law of Inertia/Equilibrium?
Newton’s Law (Law #1) that states that a body at rest will remain at rest and a body in motion will stay in motion until an outside force acts upon it
Newton’s second law of motion?
The acceleration of a body is proportionate to the magnitude of the forces acting on it and inversely proportionate to the mass of the body
–> a greater force is required to move a larger mass
Newton’s third law of motion?
For every action force there is an equal and opposite reaction force
What is the term for a simple machine consisting of a rigid bar that rotates around a fulcrum or axis?
Lever
3 elements of mechanical levers?
- Axis
- Resistance Arm (RA)
- Force Arm (FA)
First class lever?
Axis is in the middle of the FA and RA
Second class lever?
The RA lies between the axis and the FA; the RA is always closer to the axis than the FA
Why does the RA have the advantage in a second class lever?
Because with its location closer to the axis, larger weights can be moved using smaller amount of force
Third class lever?
The FA lies between the axis and RA; the RA is longer than the FA so it has the advantage
What’s the most common lever type in the body?
Third
What is the equation for calculating mechanical advantage?
Force Arm length/Resistance Arm length
What is mechanical advantage?
the ability to counter resistive forces in a lever system
FA>RA
greater than 1
2nd class
FA<RA
less than 1
3rd class
FA=RA
equal
1st class
What is torque?
The rotary force around an axis
True or False: Torque is greater near the axis; as opposed to further out?
False; Torque is greater further out
True or False: if torque is the same, force required near the axis is greater than further out?
True
What’s the term for the point where the mass of the body is equally distributed; it is constantly changing?
Center of Mass (COM)
What’s the term for the direction where the mass of the body is equally distributed against gravity; this cannot be controlled
Center of Gravity (COG)
What’s the term for the area that has the greatest amount of stability within the body?
Base of Support
For the greatest amount of stability, what two things must be close to one another?
COG and BOS
With regards to levers, what is the resistance force?
Weight
With regards to levers, what is the force arm refer to?
Moving force
