Lecture 3_190606 Flashcards

1
Q

Newton’s Laws

A

1) on object in motion stays in motion … at rest stays….
2) until acted on by a force, F(N) = m(kg)*a(m/s^2)
3) for every action there is an equal and opposite reaction

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2
Q

Mass (kg)

A

m = F(N)/a(m/s^2)

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3
Q

Velocity (m/sec)

A

v = Δx/Δt

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4
Q

Acceleration (m/sec2)

A

a = Δv/Δt

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5
Q

Force (kg * m/sec2)

A

F = m * a

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6
Q

Scalars

A

magnitude and units, but NOT direction

  • distance
  • speed
  • mass
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7
Q

Vectors

A

magnitude, units, and direction

  • displacement
  • velocity
  • weight
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8
Q

Fundamental forces

A

1) nuclear force (strongest)
2) electromagnetic force
4) gravitational force (weakest)

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9
Q

Nuclear force

A

Strongest

Holds protons & neutrons together in nucleus

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10
Q

Electromagnetic force

A

Holds electrons in atoms, tries to force protons apart

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11
Q

Gravitational force

A

Weakest

Holds earth in sun’s orbit and keeps you from floating away

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12
Q

Gravitational constant & Gravity

A

F.earth = G * m.earth * m / r.earth^2

g ~ 9.8m/s^2

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13
Q

lb vs kg

A

lb = force
kg = mass
2.2 lb / kg

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14
Q

N

A

= kgg = kgm/s^2 = force

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15
Q

Scales

A

measure weight

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16
Q

Balances

A

measure mass

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17
Q

Density

A

mass / volume = g/ml = g/cm^3, kg/m^3

density of water = 1g / 1ml

18
Q

Specific gravity

A

density of substance / density of water

*unit-less

19
Q

Pressure

A

= Force / Area

1 N / m2 = 1 Pa

20
Q

Atmospheric Pressure

A

1 atm = 760 mm Hg = 760 Torr = 101.325 kPa = 14.7 psi

= 29.9 inches of Hg

21
Q

Barometer

A

Compares atmospheric pressure to a vacuum

Patm = ρ * g * h – density, gravity, height

22
Q

Manometer

A

Compares atmospheric pressure to an unknown pressure

ΔP = ρ * g * Δh

23
Q

Aneroid Bellow Gauge

A

Use expansion of bellows by pressure

*useful for small or low pressures

24
Q

Bourdon Gauge Use

A

coiled tube that “straightens” in response to pressure
*useful for high pressures
Ptotal = Pgauge + Patm

25
Q

Work

A

a force acting through a distance
W = F (N) * d (m) – so N * m
1 N * m = 1 J (Joule) = 1 kg * m^2 / sec^2

26
Q

Energy

A

The units for energy and work are the same – Joules (N*m or kg * m^2 / sec^2)

Another unit for energy =
1 calorie = energy needed to increase temp of 1g of H2O 1ºC NOTE: the “food” calorie, always written Calorie, is really a kcal (1000 calories). 1 kcal = 1000 cal = 4184 J

27
Q

Kinetic Energy

A

KE = ½ * m * v2 = kg * m^2 / sec^2

28
Q

Potential Energy

A

PE = m * g * h = kg * m^2 / sec^2

29
Q

Internal Energy

A

The total energy of a system (kinetic energy + potential energy)

30
Q

Potential Energy & Work

A

Imagine lifting an object
F = m * g
If I lift the object “d” distance up, then W = m * g * d
The increase in potential energy is ΔPE = m * g * d = W

31
Q

Kinetic Energy & Work

A

Imagine pushing a car, and accelerating it:
a = F / m
Let’s assume I push with constant force for time, t, the car speeds up
W = ΔKE = ½ m * v.final^2 – ½ m * v.initial^2

32
Q

Power

A

= Work / time

1 Watt = 1 J/sec = 1 kg * m^2 / sec^3

33
Q

Laws of thermodynamics

A

0) if temp A = temp B, then = thermal equilibrium
1) ΔU = Q + W, change in internal energy = energy put into system + work done on the system
2) Heat flows from hot to cold
3) It’s not possible to reach absolute zero

34
Q

Q > 0

A

endothermic process: energy flows into system (appears colder)

35
Q

Q < 0

A

exothermic process: energy flows out of system (appears hotter)

36
Q

W < 0

A

work done by system (expansion)

37
Q

W > 0

A

work done on system (compression)

38
Q

Heat

A

a measure of energy

39
Q

Temperature

A

related to average kinetic energy of particles
KE = 3 * k * T / 2
Where k is Boltzmann’s constant (1.38E-23 J/K), and T is temperature in Kelvin

*When we increase the average energy per particle, we increase the temperature, and vice versa

40
Q

Specific heat

A

energy necessary to change the temperature of 1 g of material by 1 degC
c = Q/(m*deltaT)

41
Q

Heat capacity

A

C = Q/deltaT