Lecture 3_190606 Flashcards
Newton’s Laws
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
Mass (kg)
m = F(N)/a(m/s^2)
Velocity (m/sec)
v = Δx/Δt
Acceleration (m/sec2)
a = Δv/Δt
Force (kg * m/sec2)
F = m * a
Scalars
magnitude and units, but NOT direction
- distance
- speed
- mass
Vectors
magnitude, units, and direction
- displacement
- velocity
- weight
Fundamental forces
1) nuclear force (strongest)
2) electromagnetic force
4) gravitational force (weakest)
Nuclear force
Strongest
Holds protons & neutrons together in nucleus
Electromagnetic force
Holds electrons in atoms, tries to force protons apart
Gravitational force
Weakest
Holds earth in sun’s orbit and keeps you from floating away
Gravitational constant & Gravity
F.earth = G * m.earth * m / r.earth^2
g ~ 9.8m/s^2
lb vs kg
lb = force
kg = mass
2.2 lb / kg
N
= kgg = kgm/s^2 = force
Scales
measure weight
Balances
measure mass
Density
mass / volume = g/ml = g/cm^3, kg/m^3
density of water = 1g / 1ml
Specific gravity
density of substance / density of water
*unit-less
Pressure
= Force / Area
1 N / m2 = 1 Pa
Atmospheric Pressure
1 atm = 760 mm Hg = 760 Torr = 101.325 kPa = 14.7 psi
= 29.9 inches of Hg
Barometer
Compares atmospheric pressure to a vacuum
Patm = ρ * g * h – density, gravity, height
Manometer
Compares atmospheric pressure to an unknown pressure
ΔP = ρ * g * Δh
Aneroid Bellow Gauge
Use expansion of bellows by pressure
*useful for small or low pressures
Bourdon Gauge Use
coiled tube that “straightens” in response to pressure
*useful for high pressures
Ptotal = Pgauge + Patm
