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kin 306 > Torques, Angular Kinetics/Kinematics > Flashcards

Torques, Angular Kinetics/Kinematics Flashcards

0
Q

Since producing torque requires force, there just be: (3)

A

Magnitude (how much)
Direction (linear and line of action)
Point of application

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1
Q

How to create more torque (without changing force):

A

Move “hand farther away from axis = inc moment arm
T= F*r
r = moment arm

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2
Q

The _______ the moment arm the greater the _______.

A

Longer/ greater

Torque

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3
Q

When forces are the _______ with a ______ moment arm = ____ _____

A

Same
Long
Greater torque

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4
Q

When is the moment arm the longest in the human body (muscle and joint systems?

A

90 degrees

- extend slightly- attachment moves closer to axis = moment arm shorter – same with < 90dg

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5
Q

What determines the amount of torus we generate?

A 
Moment arm length
Muscular force (strength of contraction)
Position/angle of the joint
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6
Q

Longer radius =

A

Greater velocity for any given angle

S=wr = change in angle / t

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7
Q

Longer club =

A

Greater linear velocity = greater displacement

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8
Q

Components of Angular Acceleration

A

Tangential

Centripetal

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9
Q

The Moment of Inertia equation applies best to:

A

Objects in which distribution of mass is constant through the rotation

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10
Q

Can angular moment be changed after leaving the ground?

A

No, but angular velocity can change (rotate faster = dec moment of inertia

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11
Q

Angular Momentum: changes in linear motion

Rigid and Non-Rigid

A
  • Rigid object: generally depends on change in angular velocity (w)
  • Non-Rigid: easily influenced by changes in avg. velocity (w) OR the moment of inertia (I)
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12
Q

Why does Newton’s 1st not require the angular velocity to remain constant?

A

change in angular velocity countered by change in moment of inertia
- H~= (dec) I * (inc) w

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13
Q

The _______ the object is immersed the ______ the ______.

A

Deeper submerged
Greater
Pressure

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14
Q

What is the name for when the buoyant force is equal to the weight of the displaced fluid?

A

Archimedes Principle

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15
Q

How does temperature effect the SG water?

A

high temp = dec SG (molecules farther apart)

Cold temps = inc SG (molecules closer together)

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16
Q

When will an object float?

A

When an object has SG less than water

- will weight less than an equal volume of water

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17
Q

When will an object sink?

A

When an object has a SG greater than water

- weight more than an equal volume of water

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18
Q

What are the two components that determine if an object will float or sink?

A

Density

Specific Gravity

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19
Q

What is a dynamic fluid force dependent on?

A

Density of fluid
SA of the object
Relative Velocity of the object to the fluid

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20
Q

What are the 2 major components of dynamic fluid force?

A

Drag

Lift

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21
Q

What are the 2 types of drag forces?

A

Surface

Form

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22
Q

Surface Drag- Cd is influenced by:

A
  1. Roughness of the object surface

2. Fluid viscosity (friction btw fluid layers)

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23
Q

Form Drag- Cd is influenced by:

A
  1. Objects shape

2. Surface texture

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24
Q

How do you reduce drag? (4)

A
  1. Make body surface/ clothing smoother
  2. Streamline shape
  3. Reduce SA exposed to flow
  4. Perform at: high altitude, in warm water, draft, run with wind
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25
Q

How does lift work on an airfoil?

A
  • flow across the top is faster than the bottom
  • creates L pressure on top and H pressure on bottom
  • pressure travels H –> L
26
Q

How does the Magnus Effect work?

A
  • H pressure builds on the surface that is spinning against the flow
  • L pressure on surface spinning “with” the flow (less resistance to flow)
  • object moves toward L pressure
27
Q

How does Bernoulli’s Principle work?

A
  • L pressure created on top ( fast moving fluids = L pressure)
  • H created on the bottom
  • H –> L
28
Q

Relationship btw Angular and Linear Velocity

A

avg linear speed of a point on a rotating obj

avg angular velocity of the object times the radius

29
Q

Angular Interpretation of Newton’s 1st

A
  • angular momentum remains constant unless acted on by an external force
    (remains in rotational motion unless acted upon)
30
Q

Angular Interpretation of Newton’s 2nd

A
  • net torque produces angular accel proportional to:
    1. Torque (magnitude) in the
    2. Direction of the torque and
    3. Inversely proportional to the Moment of Inertia
31
Q

Angular Impulse and Momentum Relationship

A
  • same as linear
  • ang impulse = ang momentum.
  • inc torque OR the time a torus is applied = inc ang momentum
32
Q

Angular Interpretation of Newton’s 3rd

A

For every torque exerted by one obj on another, there is an equal (magnitude) and opposite (direction) torque exerted by the 2nd obj on the 1st
- 2 obj share the same axis

33
Q

Eccentric Force

A
  • an external force not direct through an objects CoG
  • torque
  • linear and ang motion
34
Q

Centric Force

A
  • an external force directed through an objects CoG
  • NO torque
  • linear motion only
35
Q

Laminar Flow

A

Fluid molecules stay close to the obj surface

36
Q

Angular Motion

A

When all points on an object move in circular paths about the same axis (do NOT travel the save distance)
- angle formed by 2 lines/planes or one line and one plane intersecting

37
Q

Centripetal Acceleration

A

Linear accel directed toward the axis of rotation

38
Q

Bernoulli’s Principle

A

Fast moving fluid exerts less pressure than slow moving fluids

39
Q

Lift Force

A
  • Dynamic fluid force
  • acts PERPENDICULAR to the relative motion of the object (with respect to fluid)
  • not always upward (spoiler)
  • often generated when the obj is longer in the dimension // to the flow
40
Q

Tangential Acceleration

A

The component of linear accel tangent to the circular oath of a rotating object
- occurs even if the object continues to rotate about its axis

41
Q

Archimedes Principle

A

The size of the buoyant for is equal to the weight of the fluid displaced by an object

42
Q

Drag Force

A
  • dynamic fluid force
  • acts in OPPOSITION to the relative motion of the object (with respect to fluid)
  • tends to slow the object if it’s the only force acting
43
Q

Relative Angular Position

A

Both lines/planes can move

- elbow: forearm and upper arm can move

44
Q

Absolute Angular Motion

A

One line/plane is fixed

- elbow- move forearm, keep upper arm still = bicep curl

45
Q

Torque: Pulling at an angle (same amount of force)

A

Can pull with same amount of force and SHORTEN the moment arm

46
Q

What is the Magnus Effect?

A

A lift force created by the SPIN of an object

47
Q

Dynamic Fluid Force

A
  • forces exerted on an object as it moves through a fluid and/or as a fluid moves past the object
  • dependent on:
    1. Density of fluid
    2. SA of object
    3. Relative velocity of the object to the fluid
48
Q

2nd Class Levers

A

Wheelbarrow
Nutcracker (metal)
Human Body- ball of foot (a), plantar flexors (F), body aligned over tibia (R) _a____ ⬇️R____⬆️F

49
Q

Buoyant Fluid Forces

A
  • forces due to immersion

- acts upward (vertical) on an object immersed in fluid

50
Q

Specific Gavity

A

The ratio of the weight of an object to the weight of an equal volume of water

Weight obj/weight H2O

51
Q

Surface Drag

A

Caused by the friction btw an object’s surface and the fluid it’s moving through

  • roughness
  • fluid viscosity
  • skin friction
52
Q

Form Drag

A

Related to type of flow: laminar or turbulent

  • ⬆️ with turbulent flow
  • influenced by- object shape and surface texture
53
Q

Moment of Inertia

A
  • quantity of angular inertia
  • dependent on:
    1. Distribution of amass
    2. Axis of rotation
  • when smaller (mass closer to axis) = ⬆️ angular velocity/accel
54
Q

Torque

A
  • a turning/ rotary effect produced by force
  • product of Force and the perpendicular distance from the line of faction of the force to the axis of rotation
  • result of an OFF AXIS FORCE causing a turning effect
55
Q

3rd Class Levers

A
  • rowing (upper hand)
  • human muscle and joint systems
  • most levers within the human body
    a____⬆️F____⬇️R
56
Q

Pressure

A
  • buoyant force per unit area (N/m2)
  • acts in all directions on immersed obj
  • ⬆️ linearly with depth
57
Q

Radius of Gyration

A
  • represents an obj’s mass distribution relative to the axis
  • changes if:
    The axis of rotation changes
    Distribution of mass about the axis changes
58
Q

Moment Arm

A

Shortest distance from axis of rotation to the line of action of the force
- always perpendicular to the line of caption (right angle)

59
Q

1st Class Levers

A

Seesaw ⬇️F_____a______⬇️R
Scissors
Lever to move heavy objects
Nodding head- atlas vertebrae ( F= m contraction, R= weight of head)

60
Q

Angular Momentum if the Human Body

A

The sum of the angular momenta of ALL the BODY SEGMENTS

- approximates the overall momentum of the body

61
Q

Turbulent Flow

A

Fluid molecules flow away from the object’s surface- may create a vacuum (L pressure)

62
Q

Force Couple/Couple

A
  • a pair of non-colinear external forces, EQUAL in MAGNITUDE but OPPOSITE in DIRECTION
  • torque
  • angular motion only
63
Q

Relative Velocity

A

The difference btw an objects velocity and fluid velocity

kin 306 (3 decks)

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