FLUID MECHANICS

SET 1

1. What is the density of water at 4°C?

- A) 1.0 g/cm³

- B) 1.5 g/cm³

- C) 2.0 g/cm³

- D) 0.5 g/cm³

Answer: A) 1.0 g/cm³

2. Which principle states that the pressure applied to an enclosed fluid is transmitted equally throughout the fluid?

- A) Bernoulli's Principle

- B) Archimedes’ Principle

- C) Pascal's Principle

- D) Torricelli’s Principle

Answer: C) Pascal's Principle

3. A fluid with low viscosity is:

- A) Highly resistant to flow

- B) Likely to be a solid

- C) More likely to flow easily

- D) Always a gas

Answer: C) More likely to flow easily

4. What causes buoyant force on an object submerged in a fluid?

- A) The temperature of the fluid

- B) The density of the object

- C) The weight of the fluid displaced by the object

- D) The mass of the object

Answer: C) The weight of the fluid displaced by the object

5. According to Bernoulli’s equation, when the speed of a fluid increases, its pressure:

- A) Increases

- B) Decreases

- C) Stays the same

- D) Oscillates

Answer: B) Decreases

6. The SI unit of pressure is:

- A) Newton

- B) Joule

- C) Pascal

- D) Liter

Answer: C) Pascal

7. Which of the following is true for an ideal fluid?

- A) It has no viscosity.

- B) It is compressible.

- C) It has surface tension.

- D) It has a high density.

Answer: A) It has no viscosity.

8. Archimedes' Principle helps explain:

- A) The flow rate of fluids

- B) The behavior of gases

- C) Why objects float or sink

- D) The resistance to flow

Answer: C) Why objects float or sink

9. A hydraulic lift operates on which principle?

- A) Bernoulli’s Principle

- B) Archimedes’ Principle

- C) Pascal's Principle

- D) Newton's Second Law

Answer: C) Pascal's Principle

10. If the pressure of a fluid at a depth is 3000 Pa, and atmospheric pressure is 100,000 Pa, what is the total pressure at this depth?

- A) 97,000 Pa

- B) 100,000 Pa

- C) 103,000 Pa

- D) 130,000 Pa

Answer: C) 103,000 Pa

11. Which factor does not affect fluid pressure in a container?

- A) Depth of the fluid

- B) Density of the fluid

- C) Volume of the fluid

- D) Gravity

Answer: C) Volume of the fluid

12. The continuity equation \((A_1V_1 = A_2V_2)\) is based on which law?

- A) Conservation of mass

- B) Conservation of energy

- C) Conservation of momentum

- D) Conservation of charge

Answer: A) Conservation of mass

13. A pipe with a diameter of 2 cm has water flowing at 4 m/s. If the pipe narrows to a diameter of 1 cm, what is the new speed of the water?

- A) 2 m/s

- B) 4 m/s

- C) 8 m/s

- D) 16 m/s

Answer: D) 16 m/s

14. Bernoulli's equation assumes:

- A) The fluid has high viscosity

- B) The fluid flow is turbulent

- C) The fluid flow is steady and non-viscous

- D) The fluid is compressible

Answer: C) The fluid flow is steady and non-viscous

15. Which of these statements is true about a fluid at rest?

- A) The fluid exerts pressure in only one direction.

- B) The fluid exerts pressure equally in all directions.

- C) The fluid exerts no pressure at all.

- D) The fluid exerts pressure that varies with direction.

Answer: B) The fluid exerts pressure equally in all directions.

16. When you squeeze a balloon, the pressure inside the balloon:

- A) Decreases

- B) Increases

- C) Stays the same

- D) Depends on the initial temperature

Answer: B) Increases

17. What happens to the density of an object if it’s compressed without changing its mass?

- A) The density increases

- B) The density decreases

- C) The density remains constant

- D) It depends on the shape of the object

Answer: A) The density increases

18. In a Venturi tube, the fluid velocity at the narrowest section is:

- A) The lowest in the tube

- B) The same as in the rest of the tube

- C) The highest in the tube

- D) Dependent on the viscosity of the fluid

Answer: C) The highest in the tube

19. For an object floating in equilibrium in water, the buoyant force is equal to:

- A) The weight of the object

- B) The volume of the object

- C) The density of the object

- D) The temperature of the water

Answer: A) The weight of the object

20. The force per unit area exerted by a fluid on a surface is defined as:

- A) Volume

- B) Density

- C) Pressure

- D) Flow rate

Answer: C) Pressure

SET 2

1. Which of the following describes viscosity?

- A) A fluid's resistance to flow

- B) The density of the fluid

- C) The temperature of the fluid

- D) The speed at which a fluid flows

Answer: A) A fluid's resistance to flow

2. Which of the following statements is true about incompressible fluids?

- A) Their density varies with pressure.

- B) Their density remains constant.

- C) They are mostly gases.

- D) They have high viscosity.

Answer: B) Their density remains constant.

3. In a hydraulic system, a small force applied to a small piston results in:

- A) A smaller force on the larger piston

- B) A larger force on the larger piston

- C) No force on the larger piston

- D) Equal force on both pistons regardless of size

Answer: B) A larger force on the larger piston

4. When a fluid flows through a pipe that narrows, what happens to its speed?

- A) The speed decreases.

- B) The speed remains the same.

- C) The speed increases.

- D) The speed depends only on the fluid's viscosity.

Answer: C) The speed increases.

5. In which situation does Bernoulli's principle apply?

- A) Fluid flows with high turbulence

- B) Steady, incompressible, and non-viscous fluid flow

- C) Fluids under very high pressure

- D) Fluids with high viscosity

Answer: B) Steady, incompressible, and non-viscous fluid flow

6. What is the primary reason objects float or sink in fluids?

- A) The fluid’s temperature

- B) The fluid’s viscosity

- C) The fluid’s pressure

- D) The fluid’s buoyant force

Answer: D) The fluid’s buoyant force

7. An object in water appears to weigh less than it does in air. What causes this effect?

- A) Atmospheric pressure

- B) Buoyant force

- C) Viscosity of water

- D) Density of the object

Answer: B) Buoyant force

8. In the context of fluid mechanics, what does the term "steady flow" mean?

- A) The fluid moves at a constant velocity everywhere.

- B) The velocity at any given point in the fluid remains constant over time.

- C) The fluid is at rest.

- D) The fluid’s density changes over time.

Answer: B) The velocity at any given point in the fluid remains constant over time.

9. Which factor does NOT influence the pressure at a certain depth in a fluid?

- A) Depth of the fluid

- B) Density of the fluid

- C) Gravity

- D) Surface area of the fluid

Answer: D) Surface area of the fluid

10. In a closed container of fluid at equilibrium, what happens if pressure is applied at one point?

- A) Pressure increases only at that point.

- B) Pressure remains unchanged throughout.

- C) Pressure is transmitted equally in all directions.

- D) Pressure decreases at other points in the container.

Answer: C) Pressure is transmitted equally in all directions.

SET 3

Key Terms

1. What term describes the measure of a fluid's resistance to flow?

- A) Density

- B) Viscosity

- C) Pressure

- D) Velocity

Answer: B) Viscosity

2. What is the term for the force exerted by a fluid per unit area?

- A) Buoyancy

- B) Viscosity

- C) Pressure

- D) Velocity

Answer: C) Pressure

3. Which term describes the upward force experienced by an object immersed in a fluid?

- A) Drag

- B) Viscosity

- C) Buoyant Force

- D) Surface Tension

Answer: C) Buoyant Force

4. Which principle explains why objects float or sink based on the displaced fluid's weight?

- A) Bernoulli’s Principle

- B) Pascal’s Principle

- C) Archimedes’ Principle

- D) Newton’s Third Law

Answer: C) Archimedes’ Principle

5. The amount of mass per unit volume of a substance is known as:

- A) Pressure

- B) Density

- C) Buoyancy

- D) Viscosity

Answer: B) Density

6. What term is used to describe the flow of fluid in layers, with no disruption between them?

- A) Turbulent flow

- B) Compressible flow

- C) Laminar flow

- D) Steady flow

Answer: C) Laminar flow

7. According to which principle is the pressure applied to an enclosed fluid transmitted equally throughout the fluid?

- A) Bernoulli’s Principle

- B) Pascal's Principle

- C) Archimedes’ Principle

- D) Torricelli’s Principle

Answer: B) Pascal's Principle

8. Which term refers to the constant mass flow rate in a fluid that flows through a varying cross-sectional area?

- A) Flow Rate

- B) Conservation of Mass

- C) Continuity Equation

- D) Bernoulli’s Principle

Answer: C) Continuity Equation

9. Which term describes a fluid that has no resistance to shear stress (idealized concept)?

- A) Ideal Fluid

- B) Real Fluid

- C) Turbulent Fluid

- D) Laminar Fluid

Answer: A) Ideal Fluid

10. The phenomenon where a liquid's surface behaves as if it were covered with a stretched elastic membrane is called:

- A) Viscosity

- B) Surface Tension

- C) Capillarity

- D) Buoyancy

Answer: B) Surface Tension

PROBLEM SOLVING EXAMPLES

BASIC ELECTRICITY PRACTICE QUESTIONS

SET 1

SET 1: Resistors in Series and Parallel

1. What is the total resistance of resistors R1, R2, and R3 connected in series with values of 4Ω, 6Ω, and 10Ω?

   • A) 20 Ω

   • B) 15 Ω

   • C) 10 Ω

   • D) 8 Ω

     Answer: B) 20 Ω

2. The equivalent resistance of two resistors in parallel, R1 = 8Ω and R2 = 8Ω, is:

   • A) 8 Ω

   • B) 4 Ω

   • C) 16 Ω

     D) 32 Ω

     Answer: B) 4 Ω

3. In a series circuit, if one resistor fails (becomes an open circuit), the result will be:

   • A) The current increases

   • B) The current decreases

   • C) The circuit remains closed

   • D) The entire circuit fails

     Answer: D) The entire circuit fails

4. If three resistors (R1 = 2Ω, R2 = 4Ω, R3 = 6Ω) are in series, what is the total resistance?

   • A) 12 Ω

   • B) 10 Ω

   • C) 6 Ω

   • D) 4 Ω

     Answer: A) 12 Ω

5. When resistors are added in parallel, what happens to the total resistance?

   • A) It increases

   • B) It decreases

   • C) It stays the same

   • D) It doubles

     Answer: B) It decreases

6. For resistors in series, the voltage across each resistor adds up to:

   • A) The current across the resistors

   • B) The total voltage supplied

   • C) The resistance value

   • D) Zero

     Answer: B) The total voltage supplied

7. What is the equivalent resistance of three resistors in parallel (R1 = 6Ω, R2 = 6Ω, R3 = 12Ω)?

   • A) 2 Ω

   • B) 3 Ω

   • C) 4 Ω

   • D) 5 Ω

     Answer: A) 2 Ω

8. In a parallel circuit, if one resistor is removed, what happens to the total current?

   • A) It decreases

   • B) It remains the same

   • C) It increases

   • D) It becomes zero

     Answer: C) It increases

9. The total resistance of resistors in series is:

   • A) Equal to the sum of the individual resistances

   • B) Equal to the product of the resistances

   • C) The average of the resistances

   • D) Always lower than any individual resistance

     Answer: A) Equal to the sum of the individual resistances

10. When resistors are connected in parallel, which of the following is true?

    • A) The total resistance is greater than any individual resistor

    • B) The total current is equal to the sum of the individual currents

    • C) The voltage across each resistor is different

    • D) The total resistance is greater than the maximum resistance

      Answer: B) The total current is equal to the sum of the individual currents

SET 2: Concepts and Real-Life Applications of Resistors in Series and Parallel

1. In a series circuit of LED lights, if one LED burns out, what happens to the rest of the LEDs?

   • A) They all remain lit

   • B) Only the burned-out LED turns off

   • C) All the LEDs turn off

   • D) The brightness of LEDs increases

     Answer: C) All the LEDs turn off

2. Which application uses resistors in parallel to ensure consistent voltage across different branches?

   • A) Flashlights

   • B) Household electrical wiring

   • C) Car batteries

   • D) Microphone circuits

     Answer: B) Household electrical wiring

3. Why are resistors often used in a series configuration in voltage divider circuits?

   • A) To increase the total current

   • B) To create a specific voltage drop

   • C) To minimize heat loss

   • D) To enhance power efficiency

     Answer: B) To create a specific voltage drop

4. In which scenario would you most likely use resistors in series?

   • A) For audio systems requiring equal volume

   • B) When building a dimmer switch for lights

   • C) In power grid systems

   • D) For devices that need to shut off individually

     Answer: B) When building a dimmer switch for lights

5. If a circuit with several parallel resistors has one resistor with a significantly lower resistance value, what can be expected regarding the total current?

   • A) It will decrease significantly

   • B) It will not change

   • C) It will increase significantly

   • D) It will create a short circuit

     Answer: C) It will increase significantly

6. Why is it common to use series resistors in Christmas light strings?

   • A) To maintain equal brightness among all bulbs

   • B) To ensure the circuit remains closed if one bulb fails

   • C) To provide varying voltages to each bulb

   • D) To enable lights to flash

     Answer: B) To ensure the circuit remains closed if one bulb fails

7. When repairing electrical appliances, a technician might place resistors in parallel to:

   • A) Prevent overheating

   • B) Allow for device functions independent of each other

   • C) Increase resistance values

   • D) Enhance battery performance

     Answer: B) Allow for device functions independent of each other

8. In a household circuit, which feature relies on resistors in parallel for proper functioning?

   • A) Light switches

   • B) Multiple outlets in one room

   • C) Circuit breakers

   • D) Indoor heating systems

     Answer: B) Multiple outlets in one room

9. What happens to brightness when incandescent bulbs are connected in series?

   • A) All bulbs shine at maximum brightness

   • B) Each bulb lights up equally

   • C) The brightness decreases with each additional bulb

   • D) Brightness is inconsistent across bulbs

     Answer: C) The brightness decreases with each additional bulb

10. Why are circuit designs often preferred with resistors in parallel over series in complex devices like computers?

• A) Simplified repair process

• B) Increased safety features

• C) Preventing cascade failures

• D) Providing more options for upgrades

  Answer: C) Preventing cascade failures

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Resistors in Series Problems

1. Problem 1: Three resistors, R1 = 4Ω, R2 = 6Ω, and R3 = 10Ω, are connected in series to a 12V battery.

   • A) Equivalent Resistance: R_total = R1 + R2 + R3 = 4Ω + 6Ω + 10Ω = 20Ω

   • B) Total Current: I = V / R_total = 12V / 20Ω = 0.6A

   • C) Current Through Each Resistor: 0.6A (same current in series)

   • D) Voltage Across Each Resistor: V_R1 = I * R1 = 0.6A * 4Ω = 2.4V; V_R2 = I * R2 = 0.6A * 6Ω = 3.6V; V_R3 = I * R3 = 0.6A * 10Ω = 6V

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2. Problem 2: Two resistors, R1 = 8Ω and R2 = 12Ω, are connected in series with a voltage supply of 24V.

   • A) Equivalent Resistance: R_total = R1 + R2 = 8Ω + 12Ω = 20Ω

   • B) Total Current: I = V / R_total = 24V / 20Ω = 1.2A

   • C) Current Through Each Resistor: 1.2A (same current in series)

   • D) Voltage Across Each Resistor: V_R1 = I * R1 = 1.2A * 8Ω = 9.6V; V_R2 = I * R2 = 1.2A * 12Ω = 14.4V

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3. Problem 3: Four resistors, R1 = 1Ω, R2 = 2Ω, R3 = 3Ω, and R4 = 4Ω, are in series connected to a 10V source.

   • A) Equivalent Resistance: R_total = R1 + R2 + R3 + R4 = 1Ω + 2Ω + 3Ω + 4Ω = 10Ω

   • B) Total Current: I = V / R_total = 10V / 10Ω = 1A

   • C) Current Through Each Resistor: 1A (same current in series)

   • D) Voltage Across Each Resistor: V_R1 = I * R1 = 1A * 1Ω = 1V; V_R2 = I * R2 = 1A * 2Ω = 2V; V_R3 = I * R3 = 1A * 3Ω = 3V; V_R4 = I * R4 = 1A * 4Ω = 4V

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4. Problem 4: A series circuit of two resistors where R1 = 5Ω and R2 = 15Ω is powered by a 15V battery.

   • A) Equivalent Resistance: R_total = R1 + R2 = 5Ω + 15Ω = 20Ω

   • B) Total Current: I = V / R_total = 15V / 20Ω = 0.75A

   • C) Current Through Each Resistor: 0.75A (same current in series)

   • D) Voltage Across Each Resistor: V_R1 = I * R1 = 0.75A * 5Ω = 3.75V; V_R2 = I * R2 = 0.75A * 15Ω = 11.25V

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5. Problem 5: Two resistors, R1 = 20Ω and R2 = 30Ω, connected in series to a 60V power supply.

   • A) Equivalent Resistance: R_total = R1 + R2 = 20Ω + 30Ω = 50Ω

   • B) Total Current: I = V / R_total = 60V / 50Ω = 1.2A

   • C) Current Through Each Resistor: 1.2A (same current in series)

   • D) Voltage Across Each Resistor: V_R1 = I * R1 = 1.2A * 20Ω = 24V; V_R2 = I * R2 = 1.2A * 30Ω = 36V

Resistors in Parallel Problems

1. Problem 1: Two resistors, R1 = 4Ω and R2 = 4Ω, connected in parallel to a 12V source.

   • A) Equivalent Resistance: R_total = (R1 * R2) / (R1 + R2) = (4Ω * 4Ω) / (4Ω + 4Ω) = 2Ω

   • B) Total Current: I = V / R_total = 12V / 2Ω = 6A

   • C) Current Through Each Resistor: I_R1 = V / R1 = 12V / 4Ω = 3A; I_R2 = V / R2 = 12V / 4Ω = 3A

   • D) Voltage Across Each Resistor: V_R1 = 12V; V_R2 = 12V (same voltage in parallel)

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2. Problem 2: Three resistors, R1 = 6Ω, R2 = 3Ω, and R3 = 6Ω, connected in parallel to a 24V source.

   • A) Equivalent Resistance: 1/R_total = 1/R1 + 1/R2 + 1/R3 = 1/6 + 1/3 + 1/6 = 1Ω; R_total = 1Ω.

   • B) Total Current: I = V / R_total = 24V / 1Ω = 24A

   • C) Current Through Each Resistor: I_R1 = V / R1 = 24V / 6Ω = 4A; I_R2 = V / R2 = 24V / 3Ω = 8A; I_R3 = V / R3 = 24V / 6Ω = 4A

   • D) Voltage Across Each Resistor: V_R1 = 24V; V_R2 = 24V; V_R3 = 24V (same voltage in parallel)

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3. Problem 3: Four resistors, R1 = 2Ω, R2 = 2Ω, R3 = 4Ω, and R4 = 4Ω, connected in parallel to a 10V source.

   • A) Equivalent Resistance: 1/R_total = 1/2 + 1/2 + 1/4 + 1/4 = 3Ω; R_total = 1.33Ω.

   • B) Total Current: I = V / R_total = 10V / 1.33Ω = 7.5A

   • C) Current Through Each Resistor: I_R1 = 10V / 2Ω = 5A; I_R2 = 10V / 2Ω = 5A; I_R3 = 10V / 4Ω = 2.5A; I_R4 = 10V / 4Ω = 2.5A

   • D) Voltage Across Each Resistor: V_R1 = 10V; V_R2 = 10V; V_R3 = 10V; V_R4 = 10V.

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4. Problem 4: Two resistors, R1 = 10Ω and R2 = 5Ω, connected in parallel to a 30V source.

   • A) Equivalent Resistance: R_total = (R1 * R2) / (R1 + R2) = (10Ω * 5Ω) / (10Ω + 5Ω) = 3.33Ω

   • B) Total Current: I = V / R_total = 30V / 3.33Ω = 9A

   • C) Current Through Each Resistor: I_R1 = V / R1 = 30V / 10Ω = 3A; I_R2 = V / R2 = 30V / 5Ω = 6A

   • D) Voltage Across Each Resistor: V_R1 = 30V; V_R2 = 30V.

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5. Problem 5: Three resistors, R1 = 12Ω, R2 = 12Ω, and R3 = 12Ω, connected in parallel to a 12V power supply.

   • A) Equivalent Resistance: R_total = (R1 * R2 * R3) / (R1 * R2 + R2 * R3 + R1 * R3) = (12Ω * 12Ω * 12Ω) / (12Ω * 12Ω + 12Ω * 12Ω + 12Ω * 12Ω) = 4Ω

   • B) Total Current: I = V / R_total = 12V / 4Ω = 3A

   • C) Current Through Each Resistor: I_R1 = 12V / 12Ω = 1A; I_R2 = 12V / 12Ω = 1A; I_R3 = 12V / 12Ω = 1A

   • D) Voltage Across Each Resistor: V_R1 = 12V; V_R2 = 12V; V_R3 = 12V.