Exam 11: Fluids

The average density of the material in intergalactic space is approximately 2.5 × 10^-²⁷ kg/m³.What is the volume of a lead sample, = 11 300 kg/m³,that has the same mass as 8.0 × 10²⁴ m³ of intergalactic space?

A horizontal piping system that delivers a constant flow of water is constructed from pipes with different diameters as shown in the figure.At which of the labeled points is the water in the pipe under the greatest pressure? The drawing is a view from above the pipe.

In a classroom demonstration,a 79.2-kg physics professor lies on a "bed of nails." The bed consists of a large number of evenly spaced,relatively sharp nails mounted in a board so that the points extend vertically outward from the board.While the professor is lying down,approximately 1950 nails make contact with his body. -If the area of contact at the head of each nail is 1.26 × 10^-⁶ m²,what is the average pressure at each contact?

Within a certain type of star called a neutron star,the material at the center has a mass density of 1.0 × 10¹⁸ kg/m³.If a tiny sphere of this material of radius 1.0 × 10^-⁵ m were somehow transported to the surface of the earth,what would be the weight of this sphere?

When a block of volume 1.00 × 10^-³ m³ is hung from a spring scale as shown in Figure A,the scale reads 10.0 N.When the same block is then placed in an unknown liquid,it floats with 2/3 of its volume submerged as suggested in Figure B.The density of water is 1.00 × 10³ kg/m³. -Determine the density of the unknown liquid.

Which one of the following statements concerning fluid streamlines is true?

A balloon inflated with helium gas (density = 0.2 kg/m³)has a volume of 6 × 10^-³ m³.If the density of air is 1.3 kg/m³,what is the buoyant force exerted on the balloon?

At a location where the acceleration due to gravity is 9.807 m/s²,the atmospheric pressure is 9.891 × 10⁴ Pa.A barometer at the same location is filled with an unknown liquid.What is the density of the unknown liquid if its height in the barometer is 1.163 m?

In a car lift,compressed air with a gauge pressure of 4.0 × 10⁵ Pa is used to raise a piston with a circular cross-sectional area.If the radius of the piston is 0.17 m,what is the maximum mass that can be raised using this piston?

Elaine went to her outside faucet to fill a 0.0189-m³ bucket with water to wash her car.Water exits with a speed of 0.61 m/s.The radius of the faucet is 0.0078 m.How long does it take to fill the bucket completely?

An object weighs 15 N in air and 13 N when submerged in mineral spirits,which has a density of 788 kg/m³.Determine the density of the object.

Oil ( = 925 kg/m³)is flowing through a pipeline at a constant speed when it encounters a vertical bend in the pipe raising it 4.0 m.The cross sectional area of the pipe does not change.What is the difference in pressure (P_B - P_A)in the portions of the pipe before and after the rise?

A gas sample is confined within a chamber that has a movable piston.A small load is placed on the piston;and the system is allowed to reach equilibrium.If the total weight of the piston and load is 70.0 N and the piston has an area of 5.0 × 10^-⁴ m²,what is the pressure exerted on the piston by the gas? Note: Atmospheric pressure is 1.013 × 10⁵ Pa.

A balloon is released from a tall building.The total mass of the balloon including the enclosed gas is 2.0 kg.Its volume is 5.0 m³.The density of air is 1.3 kg/m³. -Will the balloon rise,fall,or remain stationary;and why?

Water enters a pipe of diameter 3.0 cm with a velocity of 3.0 m/s.The water encounters a constriction where its velocity is 15 m/s.What is the diameter of the constricted portion of the pipe?

A solid cylinder has a radius of 0.051 m and a height of 0.0030 m.The cylinder is composed of two different materials with mass densities of 1950 kg/m³ and 1470 kg/m³.The cylinder contains an equal mass m of each of the two materials,so that the total mass is M = 2m.What is the mass m?

A barometer is taken from the base to the top of a 279-m tower.Assuming the density of air is 1.29 kg/m³,what is the measured change in pressure?

A woman is enjoying a tropical drink while lying on a beach.The acceleration due to gravity at her location is 9.78 m/s².What gauge pressure must exist in the woman's mouth if she is drinking through a straw extending 0.075 m above the surface of the drink? Note: Assume the drink has a density of 1020 kg/m³.

Which one of the following statements concerning streamline flow is true?

A hypodermic needle consists of a plunger of circular cross-section that slides inside a hollow cylindrical syringe.When the plunger is pushed,the contents of the syringe are forced through a hollow needle (also of circular cross-section).If a 4.0-N force is applied to the plunger and the diameters of the plunger and the needle are 1.2 cm and 2.5 mm,respectively,what force is needed to prevent fluid flow at the needle?