Ch.3 Basic Biomechanical factors Flashcards
What are the 3 machines in the body?
-Lever
-Wheel/Axle
-Pulley
Components of the 3 classes of levers; FAR/RAF ARF/FRA AFR/RFA
1st class- axis (A) between force (F) & resistance (R)
2nd class- resistance (R) between axis (A) & force (F)
3rd class- force (F) between axis (A) & resistance (R)
Mechanical Advantage =
Resistance/force
A force can balance a larger resistance when the…
force arm (Fa) is longer than the resistance arm (Ra)
The longer the lever…
The more force produced
The shorter the lever…
The more speed it produces
The rotary (turning/rotational) effect of a force about an axis of rotation
Torque
-Distance between the location of force and axis
- Distance between the axis and point of resistance
-Force arm
-Resistance arm
What is 1st class lever and an some examples?
-FAR or RAF
-Produces balanced movements
Ex: Seesaw, Scissors, Crowbar, Head on neck
What is 2nd class levers and examples given?
-FRA or ARF
-Produces or multiples force movements
-Plantar flexion on foot to raise body up
3rd lever class and examples provided?
-AFR or RFA
- Produce multiple speeds and ROM which requires massive force to move small resistance
- Paddling boat, shoveling, biceps and elbow
What are wheels/axles used for?
Used primarily to enhance ROM & speed of movement in the musculoskeletal system
Why do pulleys function to do?
Change effective direction
MA=1
Difference between Linear motion and Angular motion
Linear motion is motion along a line whereas Angular motion is a rotation around the axis
Two types of Linear motion
-Rectilinear Motion- motion along a straight line
-Curvilinear Motion- motion along a curved line
Displacement vs. Distance
Displacement: Change in position or location of an object from original point(straight line)
Distance: Actual sum of length of measurement traveled
2 types of displacement
• Angular displacement: change in location of a rotating body
• Linear displacement: distance that a system moves in a straight line
A body in motion tends to remain in motion at the same speed unless acted on by a force; a body at rest tends to remain at rest unless acted on by a force
Newtons 1st Law: Law of Inertia
A change in the acceleration of a body occurs in the same direction as the force that caused it
Newton’s 2nd Law: Law of Acceleration
For every action there is an opposite and equal reaction
Newton’s 3rd Law: Law of Reaction
Force from the resistance between surfaces of two objects from moving upon one another
Friction
Types of Friction
-Static Friction
-Kinetic Friction
-Rolling Friction
What is static friction and kinetic friction?
• Static friction: friction between two objects that are not moving
• Kinetic friction: friction between two objects that are sliding
upon one another
What is Rolling friction & what is the level of friction from strongest to weakest amongst all of them?
RF: Resistance to an object rolling across a surface such as a ball rolling across a court or a tire rolling across the ground
~ SF > KF > RF
Ability to control equilibrium
Balance
• Equilibrium: no change in the speed or direction of the body
T/F: To achieve balance, stability needs to be minimized
False
• Stability: resistance to a change
Point where body’s mass is equally distributed
Center of gravity
Factors for increasing balance (BWCM)
• ↑ base of support
• ↑ weight (mass)
• ↓ the center of gravity
• Move to center of base
What pushes or pulls an object to affect motion?
Force
What is known as the quantity of motion?
Momentum
The greater the momentum…
The greater the resistance to change
How do you increase momentum?
By increasing magnitude or duration
