S1_L2: Kinetics Flashcards
It is the study of forces acting from the body. These are the driving forces that make the body move, make the body stable, or prevent it from moving.
Kinetics
A state where the body is not in motion, but forces are acting on it.
Statics / Equilibrium
A state where the body is in motion and a driving force keeps it moving.
Dynamics
A hypothetical point at which the body’s weight is equally balanced and mass of the object is concentrated
Center of Gravity (CoG) / Center of Mass (CoM)
Where is the body’s center of gravity located?
An inch anterior to S2 in anatomical position
It is the force that is the gravitational vector
Line of Gravity
TRUE OR FALSE: It is possible for the CoG to be displaced outside of the body depending on the position and movement done.
True
TRUE OR FALSE: Force (gravity) should always start in the center of gravity
True
It is a push or a pull exerted by one object or substance on another
Force
These generate or resist force in the body. Examples of these are
muscles, ligaments, tendons, menisci, joint capsule, and bones.
Internal forces
These are externally applied resistance to the body. Examples are wind, water, dumbbell, other weights, and friction.
External forces
TRUE OR FALSE: Gravity acts on the center of mass of an object and can be considered to be “touching” all objects.
True
Determine the descriptions of the force concepts
- Weight per unit of volume
- Force distributed over a given area
- Product of force and the time over which the force acts
- Mass per unit of volume
A. Impulse
B. Density
C. Specific weight
D. Pressure
- C
- D
- A
- B
Determine the descriptions of the force concepts
- SI Unit: N/m^3
- SI Unit: Pascal (Pa)
- SI Unit: kg/m^3
- SI Unit: Newton-second (N●s)
A. Impulse
B. Density
C. Specific weight
D. Pressure
- C
- D
- B
- A
Determine the descriptions of the force concepts
- Force applied over some distance
- It is the ability to perform work
- Rate of work production
- It is similar to torque
- SI Unit: Watt (W) or Joules per second (J/s)
A. Work
B. Power
C. Energy
- A
- C
- B
- A
- B
TRUE OR FALSE: Pressure is inversely proportional to the surface area of application, while work is directly proportional to force and distance.
True
Determine the corresponding descriptions of the types of parallel force systems
- Can result to fracture injuries in long bones
- Special case of torque where rotation of a segment around its long axis occurs
- Torques applied to a particular point on the object
- Rotational in nature
- Parallel forces applied on unsegmented object
A. Bending Moment
B. Torsional Moment
- B
- B
- A
- B
- A
Determine the corresponding descriptions of the types of linear forces
- Applied parallel to the long axis of object, co-linear and coplanar
- Between two objects, this is proportionate to their masses and inversely proportionate to square of distance between the center of the two objects
- Force that has an action line parallel (flat) / tangential (curved) to contacting surfaces that creates or limits movement between surfaces
- Potentially exists on an object whenever there is a contact force on the object
- Contact forces that are perpendicular to the surfaces that produce them
A. Gravitational Forces
B. Normal Forces
C. Tensile/Distractive Forces
D. Compressive Forces
E. Shear Forces (Fs)
F. Friction Forces (Fr)
- C
- A
- E
- F
- B
Determine the corresponding descriptions of the translatory forces
- Two or more non-colinear forces act on the same segment
- Two or more forces act on the same segment, in the same plane and in the same line
- Two forces of equal magnitude acting in same direction on same plane with counterforce in the middle
- Example is the forces of the ACL & PCL on the knee joint
- Example is the hamstrings and quadriceps on the knee joint
- Converging (intersecting) on same starting point or axis
A. Linear force systems
B. Parallel force systems
C. Concurrent force systems
- C
- A
- B
- C
- C
- C
Determine the corresponding classifications of the ff forces
- Compressive forces
- Tensile/Distractive forces
- Normal forces
- Electrical forces
- Gravitational forces
- Shear forces
A. Non-Contact Forces
B. Contact Forces
- B
- B
- B
- A
- A
- B
Determine the corresponding descriptions of the class lever systems in the body
- Resistance is as the center
- Primarily intended for speed and ROM
- Fulcrum is at the center
- Most common in the human body
- Example is ankle plantar flexion
- Meant for force production
A. 1st Class Lever
B. 2nd Class Lever
C. 3rd Class Lever
- B
- C
- A
- C
- A
- B
Determine the corresponding descriptions of mechanical advantage and disadvantage
- Little effort (force) to move resistance (force)
- Levers that are designed for speed / ROM
- More effort (force) to move resistance (force)
- Levers that are designed for force
A. Mechanical Advantage
B. Mechanical Disadvantage
- A
- B
- B
- A
Which law of motion states: “For every action force there is an equal and opposite reaction force”?
Newton’s Third Law of Motion: Action-Reaction
Determine the corresponding approximate anatomic location of the CoG of these body segments
- Pronator teres insertion
- Anterior to T11 vertebra
- Sphenoid sinus
- Axis of 3rd metacarpal
- Medial head of triceps adjacent to radial groove
- Inferior surface of basioccipital bone
A. Head
B. Head & neck
C. Head, neck, & trunk
D. Arm
E. Forearm
F. Hand
- E
- C
- A
- F
- D
- B
Determine the corresponding approximate anatomic location of the CoG of these body segments
- Plantar ligaments
- Just above the knee joint
- Below popliteus
- An inch anterior to S2
- Just above elbow joint
- Adductor brevis (or magnus/ vastus medialis)
A. Upper limb
B. Thigh
C. Leg
D. Foot
E. Lower limb
F. Whole body
- D
- E
- C
- F
- A
- B
Determine the corresponding descriptions of the types of linear forces
- Direction is opposite to potential movement and always parallel / tangential to contacting surfaces
- Joint reaction forces that push the segments towards each other
- One of the most consistent and influential that affects the human body (posture and movement)
- Acts on each unit of mass that composes an object
- Perpendicular forces directed towards the joint surfaces
A. Gravitational Forces
B. Normal Forces
C. Tensile/Distractive Forces
D. Compressive Forces
E. Shear Forces (Fs)
F. Friction Forces (Fr)
- F
- D
- A
- A
- D
Determine the corresponding descriptions of the class lever systems in the body
- Mechanical disadvantage
- Mechanical advantage
- Example is capital flexion
- Example is ankle dorsiflexion
- Example is the supraspinatus at humerus for shoulder abduction
- Example is knee flexion
A. 1st Class Lever
B. 2nd Class Lever
C. 3rd Class Lever
- C
- B
- A
- B
- A
- C
1 Newton (N) = ___ pound (lb)
0.225
1 pound = ___ N
4.45
TRUE OR FALSE: All forces are vector quantities.
True
Insertion to origin : (1)___ kinematic chain :: Origin to insertion : (2)___ kinematic chain
- open
- closed
The process of determining a single vector (or effect), the resultant vector
Vector Resolution
Method of vector composition where the first vector is drawn then attach the tail of the second vector to the tip of the first one. Afterwards, attaching the starting and end point of the two vectors becomes the resulting vector.
Tip-to-tail method
How much force does the left supraspinatus muscle have to exert to hold the position without the arms falling? Given:
1. distance of supraspinatus insertion = 0.01m;
2. force of deltoids = 410N; distance of deltoid insertion = 0.02m;
3. weight of UE = 3.5kg; distance of COM of UE = 0.10m;
4. weight of dumbbell = 10kg; distance of dumbbell = 0.50m
4423 N
Solution:
* (x)(0.01m) + (410N)(0.02m) + ((3.5 kg)(-9.8m/s^2) x 0.10m) + ((10 kg)(-9.8m/s^2) x (0.50m) = 0
* 8.2 + (-3.43) + (-49) = -44.23
* -0.01x = -44.23
* x = 4423 N
Which law of motion states: “The acceleration (a) of a body is proportionate to the magnitude of the net force (F) acting on it and inversely proportionate to the mass (m) of the body”?
Newton’s Second Law of Motion: Acceleration
Which law of motion states: “If a body is at rest, it will remain at rest, and if a body is in uniform motion, it will remain in motion, until an external force acts upon it”?
Newton’s First Law of Motion: Inertia
Aka Law of Equilibrium (STATICS)
Is described by the acceleration (a) of the object to which the force is applied, with the acceleration being directly proportional to the mass (m) of that object
Forces
F = (m)(a) / W = (m)(a)
TRUE OR FALSE: All forces in the same linear force system can be composed into a single resultant vector.
True
TRUE OR FALSE: The biceps brachii has a lower compressive force, but produces a greater flexion force. Conversely, the brachioradialis has a higher compressive force, but produces a lesser flexion force.
True
Concurrent force systems are forces that can be composed into a single resultant force through a graphic process known as composition by ___.
parallelogram
What acts as the fulcrum if the force does not pass through the CoM?
the Center of Mass (CoM)
Note: In these cases, rotational motion will occur
TRUE OR FALSE: For a system of forces to be in a state of equilibrium, the sum of vertical forces, the sum of horizontal forces, and the sum of the torque must all be equal to zero.
True
TRUE OR FALSE: Any change in ROM changes the muscle force.
True
TRUE OR FALSE: When an individual’s CoG falls outside their BoS, their balance and stability are challenged and they fall automatically.
False
The person will not automatically fall as other forces (strong muscles) can keep the person stable and maintain the position without falling.
TRUE OR FALSE: Anything that contacts a segment must create a force on that segment.
True
Applies for both internal and external forces
Force applied around an axis and has a tendency to rotate the body segment. It is also referred to as Moment of Force.
Torque
Positive torque goes in a (1)___ direction, while negative torque goes in a (2)___ direction.
- counterclockwise
- clockwise
Source: Levangie & Norkin, 2011
The heavier the object, the ___ acceleration occurs.
lesser
Term for the bony prominences that cause a deflection of the pull of the muscle force farther from the axis which leads to ↑ moment arm and ↑ torque-generation capacity of the muscle.
Anatomical pulley
The anterior deltoid exerts 170N at 30 degrees from the frontal plane. The posterior deltoid exerts 180N at 25 degrees from the frontal plane. Compute for the resultant force if both anterior and posterior deltoids contract together.
Law of cosine
X^2 = (180N)^2 + (170N)^2 - 2(180N)(170N)cos125°
X = 310.49 N
*Note: 125° = 180° - 30° - 25°
