Problem 1

 

1. The correct units on viscosity are

(A)  kg/(s · m)

(B)  kg · m/s

(C)  kg · s/m

(D)  kg · m/s2

 

2. 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

 

3. 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

 

4. (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%

  

5. 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

 

6. 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

 

7. 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

 

8. 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

 

9. 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

 

10. Lightning is observed and thunder is heard 1.5 s later. About how far away did the lightning occur?

(A)  620 m

(B)  510 m

(C)  430 m

(D)  370 m