Fluid and Thermal Physics Pre-exit Exam

A copper wire of length 2.0 m, cross sectional area 7.1 × 10^-6 m^2 and Young’s modulus 11 × 10^10 N/m^2 has a 200-kg load hung on it. What is its increase in length? (g = 9.8 m/s^2)

• 0.50 mm

• 1.0 mm

• 2.5 mm

• 5.0 mm

In an elastic solid there is a direct proportionality between strain and:

• Elastic modulus

• Stress

• Cross-sectional area

• Temperature

By what factor is the total pressure greater at a depth of 850 m in water than at the surface where pressure is one atmosphere? (Water density = 1.0 × 10^3 kg/m^3, 1 atmosphere pressure = 1.01 × 10^5 N/m^2, and g = 9.8 m/s^2)

• 83

• 100

• 74

• 19

Consider two steel rods, A and B. B has three times the area and twice the length of A, so Young’s modulus for B will be what factor times Young’s modulus for A?

• 3.0

• 0.5

• 1.0

• 1.5

A tire stops a car by use of friction. What modulus should we use to calculate the stress and strain on the tire?

• Young’s modulus

• Shear modulus

• Compressional modulus

• Bulk modulus

A block of wood has specific gravity 0.80. When placed in water, what percent of the volume of the wood is above the surface?

• 20%

• 0, the block sinks.

• 25%

• 80%

A piece of aluminum has density 2.70 g/cm^3 and mass 775 g. The aluminum is submerged in a container of oil (oil’s density = 0.650 g/cm^3). How much oil does the metal displace?

• 232 cm^3

• 309 cm^3

• 287 cm^3

• 1 125 cm^3

A cube of wood of density 0.78 g/cm^3 is 10 cm on a side. When placed in water, what height of the block will float above the surface? (Water density = 1.00 g/cm^3)

• 7.8 cm

• 5.0 cm

• 6.4 cm

• 2.2 cm

A stream of water of density ρ, cross-sectional area A, and speed v strikes a wall that is perpendicular to the direction of the stream, as shown in the figure above. The water then flows sideways across the wall. The force exerted by the stream on the wall is:

The force exerted by the stream on the wall is:

• A. ρ풗

• B. ρ vA/2

• C. ρghA

• D. 푣A/2 ρ