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Biomechanics 2241 > LECTURE #11 - work, power & energy > Flashcards

LECTURE #11 - work, power & energy Flashcards

1
Q

what is “work, power, and energy” about ?

A
  • continuation of linear kinetics
  • causes of motion do not rely on solely newtons law of motion but also the relationships between work, energy, and power
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2
Q

what is work ?

A

product of force and amount of displacement in the direction of that force

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3
Q

what is displacement ?

A

the parallel displacement component relative to the force applied

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4
Q

what is the formula for work ?

A

W = F x d (force x displacement)

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5
Q

what is F = ?

A

average force computed over distance

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6
Q

what is the formula for work ?

A

J “joules”

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7
Q

what are the three things you need for calculating work ?

A
  • average force acting on object
  • direction of object acting on object
  • displacement of object doing the line of action of the force during the time force act on it
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8
Q

what is a vector quantity ?

A

magnitude and direction

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9
Q

what are the two types of work ?

A

positive and negative work

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10
Q

what is positive work ?

A

if F and d parallel point in the same direction the work done is positive (going up)

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11
Q

what is negative work ?

A

if F and d parallel point in the opposite directions the work done is negative (going down)

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12
Q

how do you calculate displacement ?

A

final position - initial position

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13
Q

TRUE OR FALSE

“muscles perform work own bony segments, type of work depends on contraction type”

A

TRUE

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14
Q

what are the three types of muscle contractions ?

A

isometric, concentric, eccentric

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15
Q

define isometric :

A

zero work

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16
Q

define concentric :

A

positive work

17
Q

define eccentric :

A

negative work

18
Q

define energy :

A

the capacity

19
Q

what are types of energy ?

A

mechanical, chemical, heat, sound, light, etc.

20
Q

what is mechanical energy ? ;

A

energy of motion

21
Q

what are the two forms of mechanical energy ?

A

kinetics energy and potential energy

22
Q

what is kinetic energy ?

A

energy of motion (only posses kinetic energy while in motion)

23
Q

what are 2 factors that influence KE ?

A
  • mass of object
  • velocity of object (large impact)
24
Q

what is potential energy ?

A

energy of position (energy due to the change of position in gravitation field)

25
Q

what is the formula for PE ?

A

mgh

26
Q

what does PE = mgh stand for ?

A

m = mass
g = acceleration due to gravity (-9.81)
h = height of something above some reference line

27
Q

FILL IN THE BLANK

“the work of a force is _______ to the cane in energy that it produces in the object acted on”

A

equal

28
Q

FILL IN THE BLANK

“change in sum of forms of energy produced by a force is _______ to the mechanical work done by that force”

A

equal

29
Q

what is the formula for W ?

A

W = TOTAL ENERGY

30
Q

with an increase in work performed, does that mean increase or decrease energy change ?

A

increase energy change

31
Q

what are two conditions requiring energy absorption ?

A
  • catch a ball
  • land from jump
    (both of which are decreasing energy)
32
Q

do muscles do positive or negative work on limbs ?

A

negative work

33
Q

force needs to absorb KE depends on :

A
  • how much KE is there to be absorbed
  • distance over which force is applied
34
Q

what is power ?

A
  • rate @ which work is done
  • rate @ which energy
35
Q

FILL OUT THE BLANK

power can be _____ or _______

A

positive or negative

36
Q

what is energy ?

A

the capacity to do work

37
Q

what is power ?

A

rate of going work

38
Q

what is potential energy ?

A

energy due to position

39
Q

what is kinetic energy ?

A

energy due to motion

Biomechanics 2241 (21 decks)

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