The mean free path of a gas is λ = 0.225m /(ρd 2 ) where d is the molecule’s diameter, m is its mass, and r the density of the gas. Calculate the mean free path of air at sea level. For an air molecule d = 3.7 × 10−10 m and m = 4.8 × 10−26 kg.
(A) 0.65×10−7 mm
(B) 6.5×10−7 m
(C) 65 nm
(D) 650 μm
A vacuum of 25 kPa is measured at a location where the elevation is4000 m. The absolute pressure, in millimeters of mercury, is nearest
(A) 425 mm
(B) 375 mm
(C) 325 mm
(D) 275 mm
(A) 4.4%The equation p(z) = p e− gz / RT0 is a good approximation to the pressure in the atmosphere. Estimate the pressure at 6000 m using this equation and calculate the percent error assuming p0 = 100 kPa and T0= 15°C.
(B) 4.0%
(C) 3.2%
(D) 2.6%
A fluid mass of 1500 kg occupies 2 m3. Its specific gravity is nearest
(A) 1.5
(B) 0.75
(C) 0.30
(D) 0.15
A viscometer is composed of two 12-cm-long, concentric cylinders with radii 4 and 3.8 cm. The outer cylinder is stationary and the inner one rotates. If a torque of 0.046 N · m is measured on the inner cylinder at a rotational speed of 120 rpm, estimate the viscosity of the liquid. Neglect the contribution to the torque from the cylinder ends and assume a linear velocity profile.
(A) 0.127 N · s/m2
(B) 0.149 N · s/m2
(C) 0.161 N · s/m2
(D) 0.177 N · s/m2
A 0.1-m3 volume of water is observed to be 0.0982 m3 after a pressure is applied. What is that pressure?
(A) 37.8 MPa
(B) 24.2 MPa
(C) 11.7 MPa
(D) 8.62 MPa
The pressure inside a 20-μm-diameter bubble of 20°C water is nearest
(A) 17.8 kPa
(B) 24.2 kPa
(C) 29.4 kPa
(D) 38.2 kPa
A car with tires pressurized to 270 kPa (40 psi) leaves Phoenix with the tire temperature at 60°C. Estimate the tire pressure (gage) when the car arrives in Alaska with a tire temperature of –30°C.
(A) 270 kPa
(B) 210 kPa
(C) 190 kPa
(D) 170 kPa
Lightning is observed and thunder is heard 1.5 s later. About how far away did the lightning occur?
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