L13 Flashcards

1
Q

Angular motion occurrs when:

A

All parts of a body move through the same angle but do not undergo the same linear displacement

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2
Q

Angular kinematic describes

A

Angular motion without regard to the causes of the motion

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3
Q

Most human motion is a result of

A

Angular motion of the limbs that occur around joints

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4
Q

Degree: one circle/ one complete rotation

A

360 degrees

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5
Q

Revolution/ Number of rotations per one circle

A

One revelution

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6
Q

Radian: one circle= 2 pi radians

A

1 rad= 57.3 degrees

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7
Q

How to convert degrees to radians: ex 50 degrees

A

50 degrees/ x = 360 degrees/ 2 pi rad
-divide the degrees by x, equal it to 360 divided by 2 pir, then cross multiply to get 2pirad x 50 =360(x), solve for x by dividing 50 x 2pi radians by 360

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8
Q

How to convert radians to revolutions: ex 10 radians

A

10 rad/ x = 2 pi radians/ 1
-cross multiply to get 2 pi rad x (x) =1 (10 rad), so divide 1 (10rad) by 2 pi radians

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9
Q

How to convert revolutions to degrees: ex 3.3 revolutions

A

3.3rev/ x = 1rev/ 360 degrees
-cross multiply to get (3.3)(360) = 1(x), then divide by 1 to isolate x

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10
Q

Angular position

A

Orientation of a line with another line or plane

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11
Q

Absolute angular position (angle)

A

Angle of a single body segment with respect to a known vertical or horizontal
Ex) angle of the trunk is calculated with respect to the vertical plane

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12
Q

Relative Angular Position (angle)

A

-angle of one refment relative to another
-angle between longitudinal axes of 2 segments
Ex) angle of the trunk is calculated with respect to the knee, hip, and torso

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13
Q

Absolute segment angles

A

Calculated using tan
Tan: the ratio of the side opposite the angle and the size adjacent to the angle
TOA

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14
Q

Absolute Segment values calculated using

A

Tan= TOA
(Yproximal- Ydistal) / (Xproximal- X distal)

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15
Q

Relative angles use:

A

Law of Cosine
-relationship between the side of a triangle that doesn’t contain a right angle
CAH
-adjacent/ hypotenuse

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16
Q

Relative angles: law of Cosines uses:

A

Pythagoreans theorem
A= square root of (Xprox- X dist) squared + (Yprox- Ydist) squared
-need to use for all 3 side lengths of a triangle

Then: find cos for angle of triangle

17
Q

Axis of rotation

A

-fixed line about which a rigid body rotates
-always perpendicular to its plane

18
Q

Axis of Rotation

A

-direction of a rotation of angular motion referred to as the polarity of the vector

19
Q

Right Hand Rule

A

-fingers curl the same direction as the rotation of the limb trying to determine the rotation of
-if thumb is pointing right or up, it is positive
-if thumb is left or down, it is negative

20
Q

Angular distance is

A

The sumn of all angular changes (scalar)

21
Q

Angular Displacement is:

A

The difference between the final and initial positions (vector)

22
Q

Angular Displacement calculated by:

A

Change in angle= angle final- angle initial
Ex) 170 degrees- 5 degrees
Final change in angle= 165 degrees

23
Q

Linear displacement of a point on a rotating object or rigid body is directly proportional to

A

The distance that point is from the axis of rotation
-the greater the radius, the greater the linear displacement

24
Q

Linear Displacement

A

L= change in angle x radius
L= length of arc
Change in angle= angle measured in radians
R= radius

25
Q

The larger the radius of rotation (r),

A

The greater the linear distance travelled by a point of a rotating object or rigid body

26
Q

Angular speed

A

The angular distance travelled per unit of time as a scalar quantity

27
Q

Angular velocity

A

Omega (w)
-vector quantity that describes the time rate of change of angular position (in rad/s or degrees/ s)
W= change in angle/ change in time
(Final angle- initial angle)/ change in time

28
Q

Average Angular Velocity

A

Calculated anglular velocity for the object or rigid body through a certain angular displacement

29
Q

Instantaneous Angular Velocity

A

Calculated angular velocity at a specific instant when an object or rigid body is rotating

30
Q

Angular Acceleration

A

Alpha (weird a)
-rate of change in angular velocity measured inn radians per second squared or in degrees per second squared
Alpha= change in angular velocity/ change in time
(Final angular velocity- initial angular velocity) / change in time