Phyhsics questions

Chapter 7 Fluids. Chapter 8. Motion of fluids

Question 1

A container consists of two vertical cylindrical columns of different diameter connected by a narrow horizontal section, as shown in the figure. The open faces of the two columns are closed by very light plates that can move up and down without friction. The tube diameter at A is 35.0 cm and at B it is 10.2 cm. This container is filled with oil of density 0.820 g/cm3. If a 125-kg object is placed on the larger plate at A, how much mass should be placed on the smaller plate at B to balance it?

Question 2

As shown in the figure, water (density 1000 kg/m^3) is flowing in a pipeline. At point 1 the water speed is 5.90 m/s. Point 2 is 5.20 m above point 1. The cross-sectional area of the pipe is0.0800 m^2 at point 1 and 0.0200 m^2 at point 2. What is the pressure difference P1 - P2 between points 1 and 2? Treat the water as an ideal incompressible fluid. 

 

Question 3

Calculate the pressure exerted on the ground due to the weight of person standing on one foot. if the bottom of the person's foot is 13cm wide and 28cm long.

Hint: Pressure = Force/ Area

1. 4.8 × 104 Pa

2. 2.1 × 104 Pa

3. 2.2 × 103 Pa

4. 5.3 × 104 Pa

Question 4

A block of metal weighs 40 N in air and 30 N in water. What is the buoyant force on the block due to the water? The density of water is 1000 kg/m3. 

Hint: Archimedes's Principle

1. 10 N

2. 30 N

3. 70 N

4. 40 N

Question 5

A plastic block of dimensions 2.00 cm × 3.00 cm × 4.00 cm has a mass of 30.0 g. What is its density?

Hint: Density = mass / volume

1. 1.25 g/cm3

2. 1.60 g/cm3

3. 0.80 g/cm3

4. 1.20 g/cm3

Question 6

Under standard conditions, the density of air is 1.29 kg/m3. What is the mass of the air inside a room measuring 4.0 m × 3.0 m × 2.0 m?

Hint: mass = density x volume

1. 3.1 kg

2. 31 kg

3. 19 kg

4. 0.32 kg

5. 1.9 kg

Question 7

Fluid flows at 2.0 m/s through a pipe of diameter 3.0 cm. What is the volume flow rate of the fluid?

Hint: Volume flow rate = velocity x area

1. 5.7 × 10-3 m3/s

2. 57 m3/s

3. 14 m3/s

4. 1.4 × 10-3 m3/s

Question 8

A fluid is flowing with an average speed of 1.5 m/s through a tube that has a radius of 2.0 mm and is 18 cm long. The drop in pressure is 967 Pa. What is the viscosity of the fluid?

Hint: Use Poiseuille's Equations 

1. 0.028 N ∙ s/m2

2. 0.0034 N ∙ s/m2

3. 0.0056 N ∙ s/m2

4. 0.013 N ∙ s/m2

5. 0.0018 N ∙ s/m2

Question 9

Water flows through a pipe. The diameter of the pipe at point B is larger than at point A. Where is the water pressure greatest?

Hint: Remember that: P + g(density)h + 0.5(density)v^2 = constant

1. at point A

2. at point B

3. It is the same at both A and B.