Question 1

The pressure drop in a tube carrying a viscous fluid is described by

Accepted Answer

Poiseuille's equation describes the pressure drop in a tube carrying a viscous fluid. Bernoulli's principle applies to fluid flow through a pipe with varying cross-sectional area, Pascal's principle relates to pressure transmission in fluids in containers, Archimedes' principle deals with buoyancy force, and Newton's Second law describes the relationship between force, mass, and acceleration.

Question 2

The fact that a pin placed carefully on the surface of the water can remain there without sinking is best explained by

Accepted Answer

The surface tension of the water is what allows the pin to remain on top of the water. Surface tension is the cohesive force between the water molecules at the surface, creating a sort of "skin" that resists penetration by the pin.

Question 3

The fact that a dew drop is spherical is best described in terms of

Accepted Answer

The reason for the spherical shape of a dew drop is surface tension. This is the force that exists on the surface of a liquid because of the imbalance in intermolecular forces at the surface. The forces attract the liquid molecules towards each other, which minimizes the surface area of the liquid. Consequently, when a dew drop forms on a surface due to condensation, the force of surface tension pulls the liquid into a shape with minimal surface area, which is a sphere.

Question 4

When soup gets cold, it often tastes greasy. This "greasy" taste seems to be associated with oil spreading out all over the surface of the soup, instead of staying in little globules. This is readily explained in terms of

Accepted Answer

The answer of When soup gets cold, it often tastes...

Question 5

A sphere is constructed of two concentric pieces. The inner part is a solid sphere of radius 10.0 cm made of a material with density 4000 kg/m³. The outer part is a spherical shell with inner radius 10.0 cm and outer radius 20.0 cm. The outer shell has a density 9000 kg/m³. (a) What is the mass of this sphere? (b) What is the average density of this sphere?

Accepted Answer

The answer of A sphere is constructed of two concentric...

Question 6

The deepest point of the Pacific Ocean is 11,033 m, in the Mariana Trench. What is the water pressure at that point? The density of seawater is 1025 kg/m³.

Accepted Answer

At the deepest point of the Pacific Ocean, the water pressure can be calculated using the formula:

pressure = density x gravity x depth

density = 1025 kg/m^3 (given)

gravity = 9.81 m/s^2 (standard value)

depth = 11,033 m (given)

Plugging in these values, we get:

pressure = 1025 kg/m^3 x 9.81 m/s^2 x 11,033 m
pressure = 1.09 x 10^8 Pa

Rounding off to two significant figures, the answer is 1.1 x 10^8 Pa or 1.11 x 10^8 Pa, which is closest to option C.

Question 7

Substance A has a density of 3.0 g/cm³ and substance B has a density of 4.0 g/cm³. In order to obtain equal masses of these two substances, the ratio of the volume of A to the volume of B will be equal to

Accepted Answer

The answer of Substance A has a density of 3.0...

Question 8

A sphere of radius 10.0 cm floats in equilibrium partially submerged in water with its lowest point 5.00 cm below the water's surface.
(a) What is the buoyant force acting on the sphere?
(b) What is the weight of the sphere?

Accepted Answer

The answer of A sphere of radius 10.0 cm floats...

Question 9

A 1938 nickel has a diameter of 21.21 mm, a thickness of 1.95 mm, and weighs 0.04905 N. What is its density?

Accepted Answer

The answer of A 1938 nickel has a diameter of...

Question 10

The small piston of a hydraulic lift has a diameter of 8.0 cm, and its large piston has a diameter of 40 cm. The lift raises a load of 15,000 N.
(a) Determine the force that must be applied to the small piston.
(b) Determine the pressure applied to the fluid in the lift.

Accepted Answer

The answer of The small piston of a hydraulic lift...

Question 11

A U-tube with a cross-sectional area of 1.00 cm² is open to the atmosphere at both ends. Water is poured into the tube until the water rises part-way along the straight sides, and then 5.00 cm³ of oil is poured into one end. As a result, the top surface of the oil ends up 0.550 cm higher than the water surface on the other side of the U. What is the density of the oil?

Accepted Answer

The answer of A U-tube with a cross-sectional area of...

Question 12

A 100-kg person sits on a 5-kg bicycle. The weight is borne equally by the two wheels of the bicycle. The tires are inflated to a gauge pressure of 8.0 x 10⁵ Pa and are 2.0 cm wide. What length of each tire is in contact with the ground?

Accepted Answer

The weight of the person and the bicycle is 105 kg, which is 1030 N. Each wheel supports half of this weight, or 515 N. The area of contact of each tire with the ground is:$$A = \frac{F}{P} = \frac{515 	ext{ N}}{8.0 	imes 10^5 	ext{ Pa}} = 6.44 	imes 10^{-3} 	ext{ m}^2$$The length of each tire in contact with the ground is:$$L = \frac{A}{w} = \frac{6.44 	imes 10^{-3} 	ext{ m}^2}{2.0 	imes 10^{-2} 	ext{ m}} = 0.322 	ext{ m} = 32.2 	ext{ cm}$$

Question 13

A basketball player pushes down with a force of 50 N on a basketball that is inflated to a gauge pressure of 8.0 x 10⁴ Pa. What is the diameter of contact between the ball and the floor?

Accepted Answer

The force exerted by the basketball player is equal to the force exerted by the air inside the ball on the floor. The force exerted by the air is equal to the gauge pressure times the area of contact. The area of contact is equal to the area of a circle with diameter d. Therefore, we have:$$F = P_g * A$$$$F = P_g * \pi * d^2 / 4$$$$d = \sqrt{4F / (\pi * P_g)}$$$$d = \sqrt{4 * 50 N / (\pi * 8.0 x 10^4 Pa)}$$$$d = 0.028 m = 2.8 cm$$

Question 14

The flow of water emerging from a hole in a container is best described in terms of

Accepted Answer

Torricelli's law describes the flow of water from a small hole in a container, specifically the speed of the water emerging from the hole. Pascal's principle deals with pressure in a static fluid, Archimedes' principle deals with buoyancy, Poiseuille's equation describes the flow of fluids through a pipe or tube, and Newton's Second law deals with the motion of objects under the influence of forces.

Question 15

A 1959 penny has a diameter of 19.55 mm, a thickness of 1.55 mm, and a mass of 2.500 g. What is its density?

Accepted Answer

The density of an object is its mass per unit volume. The volume of a cylinder is given by the formula V = πr²h, where r is the radius and h is the height. The radius of the penny is 19.55 mm / 2 = 9.775 mm, and the height is 1.55 mm. So, the volume of the penny is V = π(9.775 mm)²(1.55 mm) = 464.5 mm³. The mass of the penny is 2.500 g. So, the density of the penny is ρ = m/V = 2.500 g / 464.5 mm³ = 5.38 × 10³ kg/m³.

Question 16

The density of air is 1.29 kg/m³. What is the mass of the air inside a room 4.0 m × 3.0 m × 2.0 m?

Accepted Answer

The volume of the room is 4.0 m × 3.0 m × 2.0 m = 24 m³. 
Using the formula: density = mass/volume, we can rearrange to solve for mass: mass = density × volume. 
mass = 1.29 kg/m³ × 24 m³ = 31 kg. 
Therefore, the mass of air inside the room is 31 kg. 
The best choice is C.

Question 17

A piece of aluminum with a mass of 1.0 kg and density of 2700 kg/m³ is suspended from a string and then completely immersed in a container of water. The density of water is 1000 kg/m³. (a) Determine the volume of the piece of aluminum. (b) Determine the tension in the string after the metal is immersed in the container of water.

Accepted Answer

The answer of A piece of aluminum with a mass...

Question 18

The weight of a 1200-kg car is supported equally by the four tires, which are inflated to the same gauge pressure. What gauge pressure is required so the area of contact of each tire with the road is 100 cm²?

Accepted Answer

The weight of the car is supported by the four tires, so the weight supported by each tire is:

W = (1200 kg)/(4) = 300 kg

The area of contact of each tire with the road is given as:

A = 100 cm^2 = 0.01 m^2

Assuming that the gauge pressure is the same in all tires, we can use the formula:

P = F/A

where F is the force exerted by each tire on the ground, given by:

F = W = 300 kg × 9.8 m/s^2 = 2940 N

Substituting the values, we get

P = 2940 N / 0.01 m^2 = 2.94 × 10^5 Pa

This is the gauge pressure required in each tire. However, the question asks for the answer in scientific notation with two significant figures. Rounding off to two significant figures and expressing in scientific notation, we get:

P = 2.9 × 10^5 Pa

which is closest to option C.

Question 19

When you blow some air above a paper strip, the paper rises. This is because

Accepted Answer

When air moves faster, according to Bernoulli's principle, the pressure decreases. Therefore, the air above the paper, which is moving faster than the air below the paper, causes a low-pressure zone above the paper, allowing it to rise.

Question 20

The Aswan High Dam is 111 m high. What is the water pressure at the foot of the dam?

Accepted Answer

The water pressure at the foot of the dam can be calculated using the formula P = ρgh, where ρ (density of water) is approximately 1000 kg/m³, g (acceleration due to gravity) is 9.8 m/s², and h (height) is 111 m. This gives P = 1000 * 9.8 * 111 = 1.09 × 10⁶ Pa.

Quiz 15: Fluids

The pressure drop in a tube carrying a viscous fluid is described by

The fact that a pin placed carefully on the surface of the water can remain there without sinking is best explained by

The fact that a dew drop is spherical is best described in terms of

When soup gets cold, it often tastes greasy. This "greasy" taste seems to be associated with oil spreading out all over the surface of the soup, instead of staying in little globules. This is readily explained in terms of

The deepest point of the Pacific Ocean is 11,033 m, in the Mariana Trench. What is the water pressure at that point? The density of seawater is 1025 kg/m3.

Substance A has a density of 3.0 g/cm3 and substance B has a density of 4.0 g/cm3. In order to obtain equal masses of these two substances, the ratio of the volume of A to the volume of B will be equal to

A sphere of radius 10.0 cm floats in equilibrium partially submerged in water with its lowest point 5.00 cm below the water's surface. (a) What is the buoyant force acting on the sphere? (b) What is the weight of the sphere?

A 1938 nickel has a diameter of 21.21 mm, a thickness of 1.95 mm, and weighs 0.04905 N. What is its density?

The small piston of a hydraulic lift has a diameter of 8.0 cm, and its large piston has a diameter of 40 cm. The lift raises a load of 15,000 N. (a) Determine the force that must be applied to the small piston. (b) Determine the pressure applied to the fluid in the lift.

A 100-kg person sits on a 5-kg bicycle. The weight is borne equally by the two wheels of the bicycle. The tires are inflated to a gauge pressure of 8.0 x 105 Pa and are 2.0 cm wide. What length of each tire is in contact with the ground?

A basketball player pushes down with a force of 50 N on a basketball that is inflated to a gauge pressure of 8.0 x 104 Pa. What is the diameter of contact between the ball and the floor?