BIOMECHANICS TEST 3

Four function of simple machine

1. balance two or more forces 2. provide advantage in force 3. provide advantage in linear range of motion and speed of movement 4. change the effective direction of the applied force

Three Characteristics of force

1. magnitude 2. direction 3. point of application

Moment of inertia depends on which factors

1.quanity of rotating mass 2. its disturbution around the axis 3.Mass 4. r= perpendicular distance between the mass particle and axis or rotation

Produces balanced movements when axis is midway between force and resistance

1st

can serve all four functions of a simple functions

1st

neck extensors and cervical extension

1st

seesaw

1st

Crowbar

2nd

favors force production

2nd

force lever arm will always be longer than the resistance lever arm. ( smaller force an move larger load)

2nd

most efficient configuration but least common within the body

2nd

produces force motion when axis is close to resistance

2nd

pushup

2nd

raising body up on toes

2nd

resistance is always closer to axis than the force

2nd

wheelbarrow

2nd

Favors resistance advantage as well as speed and ROM

3rd

biceps in elbow flexion

3rd

hamstrings contracting to flex at knee while standing

3rd

lever of force is always closer to the axis

3rd

most common in the body

3rd

produces speed and ROM when axis is close to force

3rd

requires a great deal of force to even move a small resistance

3rd

resistance lever arm is always longer than the force lever arm

3rd

Most resting muscle have and angle of pull?

< 90

Short lever arms enhance_____ while sacrificing ______&________

Angular velocity, linear speed, ROM

Define and State the Equation for Momentum

Any change in momentum is equal to the impulse that produces it force applied in direction of motion will increase momentum. Force applied in the opposite direction of motion will decrease momentum

What principle explains why some things float and some things sink? buoyancy

Archimedes Pricniple

Fluid forces buoyancy drag and lift do not regard he same laws amd principles of normal forces

Fasle they do

Parallel Forces

Forces not in the same action line but parallel to each other Ex: two forces upward one downward

Define Force

Is that which pushes or pull through direct mechanical contact

Newton's first law of motion

Law of Inertia and object at rest remains at rest and object in motion stays in motion unless acted upon by an outside force F=/ 0

Newtons 3rd law of motion

Law of reaction for every action there is an equal opposite reaction F=-F

If an angle of pull is less than 90 degrees then _____ force is directed towards the _____ and help stabilizes_____.

Non-rotary, fulcrum, joint

Work

W=Fs work is the product of force expended and the distance over which force is applied

Concurrent Forces

act at the same point of application at different angles

muscular angle of pull is the ________ between the line of pull and mechanical axis of the bone.

angle

What is the product of moment of inertia (I) and angular velocity (w)

angular momentum

angle of pull > 90

dislocating force is directed away from fulcrum does not occur often

A force whose direction is not line with the center of gravity of a freely moving object or the center of rotation of an object with a fixed axis of rotation is called

eccentric force

Specfic gravity <1

floats

angle of pull 90

force is all rotary

Linear Forces

forces apllied in the same direction the resultant is the sum of the forces

X-axis

horizontal component is always the axis of the bone non-rotary component

For perfectly elastic objects the angle of ____ is equal to the angle of _______

incidents, reflection

Lever

is a simple machine consisting of a rigid bar that rotates about fulcrum

Laminar Flow

is a smooth unbroken flow of fluid around a object

Elasticity

is the ability to resist distorting influences and to return to the original size and shape

energy

is the capacity to do work

Force Couple

is the effect of equal parallel forces acting in opposite direction

Potential Energy

is the product of weight of an object and the distance over which it can act

Drag

is the resistance to forward motion through a fluid

Newton's second law of motion

law of acceleration and object is directly proportional to the force causing it and inversely proportional to the mass of the object F=ma

the amount of torque is determined by

length of moment arm or force

When force is applied in line with a freely moving object center of gravity

linear motion occurs

Composite forces on the body are classified as what according to their direction and application?

linear,concurrent, or parrael

I= Emr^2

m=Mass r= perpendicular distance between the mass particle and axis of rotation

Torques are vector quantities which means in regards to summation of torques what must be considered

magnitude direction point of application

Free body Diagram

magnitude, direction, point of application, weight (m), Reactive force (R), friction(f)

the perpeidicular distance between force vector and the axis is called

moment arm

clock wise torque sare

negative

The sum of two or more torques may result in

no motion linear motion or rotary motion

What component of the force is the only factor in torque production?

only rotary component

For muscular force_________ between the line of force and the mechanical axis of the bone joint angle.

point of application

What type of motion occurs when the force applied is directed through the center of gravity of an object?

point of application

counter clock wise are

postive

power

rate at which work is done

Specific Gravity

ratio of the density of an object to the density of water

Density

ration of weight of an object to its volume

angle of pull 45

rotary and non rotary components are equal

Direction of a muscular force vector is in the________ of the line of pull of muscle

same direction

Specfic Gravity >1

sinks

stress and strain are defined as

stress is the force that acts to distort strain. Strain is the distortion that occurs

magnitude is?

the amount of force being applied EX: BENCH PRESS

The larger the angle of pull from 0-90 ?

the greater the y and less the x component

Ft=m(Vf-Vi) define and state the name of this equation

the product of mass and velocity and it is the equation for momentum

Coefficient of friction

the ratio of force needed to overcome the friction, to the force holding the surface together W

in regard to the principles of torques resultant torques in a force system must be equal to the sum of the torques of the individual forces of the system about the same point

true

shortening the radius of rotation increases the moment of interia and increases the angular velocity

true

the greater the distance of the fore arm the more torque produced by the force which results in increased leverage so we can move large resistance more easily

true

Y-axis

vertical component is always perpendicular to the mechanical axis of the bone rotary componet