Matter and Energy Energy = Capacity to do work W = FD W = Work (ML2/T2) F = Force (ML/T2) D = Distance (L)

Force F = ma F = Force (ML/T2) m = mass (M) a = acceleration (L/T2)

SI and English Units SI: - Mass = kilogram - Length = meter - time = second English - Mass = slug - Length = foot

Force: SI vs English SI => Newton = 1 kg m/s2 Acceleration = m/s2 English => force = pound (lb) = slug-ft/s2

Weight of a body W = mg (ML/T2) m = mass (M) g = acceleration (L/T2) Mass of body in which weight = 1 Newton: m =w/g = 1 Newton/9.8 m/s2 = 0.102 kg.

Density of a fluid ρ = m/v (M/L3) m = mass (M) v = volume (L3)

Specific Weight γ Weight per unit volume (N/m3; lb/ft3) γ = w/v (M/L2T2) γ = w/v = mg/v = ρg

Pressure Pressure = Force per unit area P = F/A (M/LT2) (N/m2; lb/ft2) Force F => (ML/T2) Area A => (L2)

Pressure – cont. P = F/A (M/LT2) (N/m2 = Pascal; lb/ft2) Hydrogeology: P is relative to atmospheric pressure (1.013 x 105 Pa or 2116 lb/ft2)

Viscosity Water => Newtonian fluid => resistance to motion is proportional to dynamic viscosity μ. μ units N s/m2 (Pa s) or lbs/ft2.

Bulk modulus or compressibility Water is a compressible fluid. Pressure applied => V reduced => density increases. K = ΔP / (ΔV/V) K is bulk modulus or proportionality constant. K units (N/m2 or Pa) => same units as pressure

Bulk Modulus = (DP/Q) … where Q = dilatation = DV/V and P = pressure