Work and Energy Flashcards

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1
Q

system’s ability to do work

A

energy

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2
Q

kinetic energy (K)

A

K = 1/2 mv^2

unit: J = kg*m^2/s^2

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3
Q

gravitational potential energy (U)

A

U = mgh

unit: J = kg*m^2/s^2

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4
Q

elastic potential energy (U)

A

U = 1/2 kx^2

unit: J = kg*m^2/s^2

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5
Q

total mechanical energy (E)

A

E = U + K

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6
Q

path dependent, conserve mechanical energy
e.g. gravitational and electrostatic forces
round-trip path: most equal zero
point-to-point path: must all be equal no matter path taken

A

conservative forces

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7
Q

conservation of mechanical energy

A
∆E = ∆U + ∆K = 0
W(conservative) = 0
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8
Q

path dependent, dissipates mechanical energy (as chemical or thermal)
e.g. friction, air resistance, viscous drag
W(nonconservative) = ∆E = ∆U + ∆K, equal to energy lost from system

A

nonconservative forces

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9
Q

method of energy transfer

A

work (also heat)

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10
Q

work (W)

A

W = Fd cos θ

unit: J = kg*m^2/s^2

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11
Q

P-V graph:
work = ?
x-axis = ?
y-axis = ?

A
work = area under curve
x-axis = volume (V)
y-axis = pressure (P)
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12
Q

constant volume process, no work

A

isochoric process

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13
Q

constant pressure process,

W = P∆V

A

isobaric process

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14
Q

rate at which energy is transferred from one system to another

A

power

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15
Q

power (P)

A

P = W/t = ∆E/t

unit: watt (W) = J/s = kg*m^2/s^3

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16
Q

work-energy theorem

A

W(net) = ∆K = K(f) - K(i)

17
Q

ratio of magnitudes of force exerted on an object by a simple machine (F(out)) to the force actually applied on the simple machine (F(in))

A

mechanical advantage

18
Q

mechanical advantage

A

mechanical advantage = F(out) / F(in)

19
Q

pulleys- what is relationship between tension and weight

A

T(total) = W

where T = tension
and W = mg

20
Q

efficiency

A

efficiency = W(out) / W(in) = (load)(load distance) / (effort)(effort distance)