How does a vacuum exert pressure?
- It exerts pressure through a force field.
- It exerts pressure through negative energy.
- It doesn’t exert pressure; the surrounding atmosphere does.
- It exerts pressure through a gravitational pull.
Correct Answer: It doesn’t exert pressure; the surrounding atmosphere does.
Correct Answer Explanation: A vacuum is simply an absence of matter. The pressure we perceive is actually the surrounding atmospheric pressure pushing in on the vacuum.
What is the “vis viva” of a moving body?
- It’s the body’s internal temperature.
- It’s the body’s potential energy.
- It’s the body’s weight.
- It’s the body’s energy of motion, measured by the square of its velocity.
Correct Answer: It’s the body’s energy of motion, measured by the square of its velocity.
Correct Answer Explanation: The term “vis viva” refers to the energy a body possesses due to its motion. This energy is proportional to the square of the body’s velocity.
What is the primary force that pushes a body outwards from a circular path?
- Centripetal force
- Gravity
- Friction
- Centrifugal force
Correct Answer: Centrifugal force
Correct Answer Explanation: Centrifugal force is the outward force a body experiences when moving in a circular path. It’s directly proportional to the body’s mass and the square of its velocity, and inversely proportional to the radius of the circular path.
What is the point in a body where its weight can be considered concentrated?
- Centre of oscillation
- Centre of gyration
- Centre of gravity
- Centre of mass
Correct Answer: Centre of gravity
Correct Answer Explanation: The center of gravity is the point where the weight of an object can be considered concentrated. This point is important for understanding how an object will balance and respond to forces.
What is the purpose of the “lap” on a slide valve?
- It ensures a smooth flow of steam.
- It controls the point of steam cutoff and the amount of expansion.
- It reduces the pressure of the steam.
- It increases the efficiency of the engine.
Correct Answer: It controls the point of steam cutoff and the amount of expansion.
Correct Answer Explanation: The lap on a slide valve is the extra length of the valve face beyond the steam port. This lap determines when the steam supply is cut off during the stroke, influencing the amount of steam expansion and the overall engine performance.
What type of boiler features a large internal flue containing the furnace?
- Wagon boiler
- Cornish boiler
- Marine flue boiler
- Marine tubular boiler
Correct Answer: Cornish boiler
Correct Answer Explanation: A Cornish boiler is characterized by its cylindrical shape and a large internal flue that houses the furnace. This design allows for efficient heat transfer and is commonly used for stationary engines.
What type of marine engine uses two beams or levers on either side of the engine?
- Oscillating engine
- Geared screw engine
- Side lever engine
- Direct acting screw engine
Correct Answer: Side lever engine
Correct Answer Explanation: A side lever engine utilizes two beams or levers on each side of the engine to connect the piston rod to the crankshaft. This design is commonly found in older marine engines and provided a more balanced and stable motion compared to other types of marine engines.
What is the primary cause of rapid internal corrosion in marine boilers?
- High pressure
- Insufficient strength
- Surcharged steam
- Scale build-up
Correct Answer: Surcharged steam
Correct Answer Explanation: Surcharged steam refers to steam containing dissolved gases and impurities. These contaminants can lead to rapid corrosion in marine boilers, especially when exposed to saltwater.
What is the approximate amount of air required for complete combustion of one pound of coal?
- 100 cubic feet
- 240 cubic feet
- 480 cubic feet
- 720 cubic feet
Correct Answer: 240 cubic feet
Correct Answer Explanation: A pound of coal typically requires around 240 cubic feet of air for complete combustion. This information is vital for designing efficient boiler systems that ensure adequate airflow for optimal combustion.
What is the average tractive force required to draw carriages on railways?
- 3.5 lbs. per ton
- 7.5 lbs. per ton
- 15 lbs. per ton
- 22.5 lbs. per ton
Correct Answer: 7.5 lbs. per ton
Correct Answer Explanation: The average tractive force needed to move carriages on railways is approximately 7.5 pounds per ton. This value accounts for factors like friction, rolling resistance, and the weight of the carriages.
What is the approximate adhesion of locomotive wheels on clean rails?
- 1/10th of the weight
- 1/5th of the weight
- 1/2 of the weight
- 3/4 of the weight
Correct Answer: 1/5th of the weight
Correct Answer Explanation: The adhesion between locomotive wheels and clean rails is around 1/5th of the locomotive’s weight. This adhesion determines the maximum force the locomotive can exert before the wheels start slipping.
In a conical pendulum, what determines its period of vibration?
- The length of the pendulum
- The mass of the weight
- The arc it describes
- The angle of the pendulum
Correct Answer: The length of the pendulum
Correct Answer Explanation: Like a simple pendulum, the period of vibration in a conical pendulum is primarily determined by its length. The angle and mass of the weight affect the speed of rotation, but not the time it takes to complete a full swing.
In a fly wheel, what is the recommended ratio of the power resident in the rim to the power generated by the engine in one half-stroke?
- 1 to 2
- 2.5 to 4
- 4 to 6
- 6 to 8
Correct Answer: 2.5 to 4
Correct Answer Explanation: The power resident in a fly-wheel’s rim should be between 2.5 to 4 times greater than the power generated by the engine in one half-stroke. This ratio helps ensure smooth and consistent power delivery, reducing fluctuations and enhancing overall engine operation.
Which of these is NOT a true statement about friction?
- Friction increases with pressure.
- Friction increases with velocity.
- Friction is a force that opposes motion.
- Friction can be reduced through lubrication.
Correct Answer: Friction increases with velocity.
Correct Answer Explanation: While friction does increase with pressure, it doesn’t necessarily increase with velocity. In some cases, friction can actually decrease with higher velocities due to the formation of a lubricating film between surfaces.
How much steam room does Boulton and Watt allow per horsepower in land wagon boilers?
- 4.75 cubic feet
- 8.75 cubic feet
- 12.75 cubic feet
- 16.75 cubic feet
Correct Answer: 8.75 cubic feet
Correct Answer Explanation: Boulton and Watt, prominent engineers of the Industrial Revolution, recommended a steam room of 8.75 cubic feet per horsepower for land wagon boilers. This ensures sufficient steam storage and efficient operation of the engine.
What is the most common cause of boiler explosions?
- Corrosion
- Scale build-up
- High pressure
- Insufficient strength
Correct Answer: High pressure
Correct Answer Explanation: High pressure is the most common cause of boiler explosions. When the pressure inside a boiler exceeds the strength of its materials, it can lead to a catastrophic failure.
What type of engine is commonly used for pumping water, often employing high-pressure steam and expansion techniques?
- Locomotive engine
- Side lever engine
- Oscillating engine
- Cornish pumping engine
Correct Answer: Cornish pumping engine
Correct Answer Explanation: Cornish pumping engines are designed for pumping water, typically using a single-acting beam mechanism. They often utilize high-pressure steam and expansion techniques for improved efficiency.
What is the approximate evaporative power of one pound of the best Welsh coal?
- 5 to 6 lbs. of water into steam
- 9.5 to 10 lbs. of water into steam
- 12 to 13 lbs. of water into steam
- 15 to 16 lbs. of water into steam
Correct Answer: 9.5 to 10 lbs. of water into steam
Correct Answer Explanation: One pound of the best quality Welsh coal can evaporate between 9.5 to 10 pounds of water into steam. This value is crucial for assessing the efficiency of boilers and calculating fuel consumption.
What is the approximate heating surface required per cubic foot of water evaporation per hour in a wagon boiler?
- 4 square feet
- 6 square feet
- 9 square feet
- 12 square feet
Correct Answer: 9 square feet
Correct Answer Explanation: A cubic foot of water evaporation per hour requires approximately 9 square feet of heating surface in a wagon boiler. This ensures adequate heat transfer and efficient steam generation.
What does the “duty” of a pumping engine refer to?
- The amount of work it can perform in a given time.
- The amount of water it can pump in a given time.
- The number of pounds of water it can raise one foot high by a bushel of coal.
- The efficiency of the engine in converting fuel into mechanical energy.
Correct Answer: The number of pounds of water it can raise one foot high by a bushel of coal.
Correct Answer Explanation: The duty of a pumping engine is a measure of its efficiency. It is expressed as the number of millions of pounds of water raised one foot high by consuming one bushel of coal.
What is the approximate range of the calorimeter of a marine flue boiler, expressed in square inches?
- 10 to 15
- 15 to 20
- 20 to 25
- 25 to 30
Correct Answer: 20 to 25
Correct Answer Explanation: The calorimeter of a boiler, which represents the sectional area of the flue in square inches, typically falls between 20 and 25 in marine flue boilers. This value is critical for ensuring efficient flue gas flow and optimal heat transfer.
How does the blast pipe in locomotive boilers affect the draught?
- It increases the draught by creating a vacuum in the smokebox.
- It reduces the draught by increasing the resistance in the chimney.
- It has no impact on the draught.
- It improves the combustion by supplying additional oxygen.
Correct Answer: It increases the draught by creating a vacuum in the smokebox.
Correct Answer Explanation: The blast pipe in a locomotive boiler is crucial for maintaining a strong draught. As steam exhausts through the blast pipe, it creates a vacuum in the smokebox, pulling air through the fire grate and providing the necessary oxygen for combustion.
What is the approximate amount of water a locomotive can evaporate per hour for each square foot of fire grate?
- 8 to 12 cubic feet
- 12 to 16 cubic feet
- 16 to 20 cubic feet
- 20 to 24 cubic feet
Correct Answer: 16 to 20 cubic feet
Correct Answer Explanation: A locomotive can evaporate approximately 16 to 20 cubic feet of water per hour for every square foot of fire grate surface area. This figure is crucial for understanding locomotive performance and determining fuel consumption.
How does the pressure of steam relate to its temperature?
- As pressure increases, temperature decreases.
- As pressure increases, temperature remains constant.
- As pressure increases, temperature increases.
- There is no relationship between pressure and temperature.
Correct Answer: As pressure increases, temperature increases.
Correct Answer Explanation: Steam pressure and temperature are directly related. As the pressure of steam increases, its temperature also rises. This relationship is essential for understanding the behavior of steam engines and boiler operations.
What is the approximate exhaustion created by the blast in locomotive boilers, expressed in inches of water?
- 2 to 3 inches
- 4 to 5 inches
- 6 to 7 inches
- 8 to 9 inches
Correct Answer: 6 to 7 inches
Correct Answer Explanation: The blast in locomotive boilers can produce an exhaustion equivalent to approximately 6 to 7 inches of water. This strong suction is critical for maintaining a vigorous draught and efficient combustion.
Which type of iron has a higher tensile strength than cast iron but a lower crushing strength?
- Cast iron
- Wrought iron
- Malleable iron
- Steel
Correct Answer: Malleable iron
Correct Answer Explanation: Malleable iron, though weaker in compression than cast iron, boasts a significantly higher tensile strength, making it better suited for applications that require resistance to pulling forces.
What is the limit of elasticity in a material?
- The maximum strain it can withstand before breaking.
- The maximum strain it can withstand before permanent deformation.
- The maximum stress it can withstand before breaking.
- The maximum stress it can withstand before permanent deformation.
Correct Answer: The maximum strain it can withstand before permanent deformation.
Correct Answer Explanation: The limit of elasticity refers to the maximum amount of strain a material can endure before undergoing permanent deformation. Once this limit is exceeded, the material will not return to its original shape.
What is the recommended maximum strain for iron used in boilers, expressed in pounds per square inch?
- 2,000 lbs.
- 3,000 lbs.
- 4,000 lbs.
- 5,000 lbs.
Correct Answer: 4,000 lbs.
Correct Answer Explanation: Iron used in boilers should not be subjected to a strain exceeding 4,000 pounds per square inch. This ensures the structural integrity of the boiler and prevents catastrophic failures.
What is the term for the insoluble salts that deposit in boilers, leading to scale formation?
- Minerals
- Salts
- Oxides
- Carbonates
Correct Answer: Salts
Correct Answer Explanation: Insoluble salts from the water used in boilers tend to deposit on the inner surfaces, forming scale. This scale can hinder heat transfer and reduce boiler efficiency.
What is the process of allowing steam to expand in the cylinder after the steam valve is closed?
- Cutoff
- Expansion
- Wire-drawing
- Lap
Correct Answer: Expansion
Correct Answer Explanation: Steam expansion refers to the process of allowing steam to expand in the cylinder after the steam valve is closed. This process increases the efficiency of the engine by extracting more work from a given amount of steam.
How is the nominal power of a condensing engine calculated?
- Squaring the diameter of the cylinder, multiplying by the piston speed, and dividing by 6,000.
- Squaring the diameter of the cylinder, multiplying by the pressure (less 1.5 lbs for friction), and the piston speed, and dividing by 42,017.
- Multiplying the cylinder area by the piston speed and dividing by 33,000.
- Multiplying the cylinder area by the pressure and dividing by 33,000.
Correct Answer: Squaring the diameter of the cylinder, multiplying by the piston speed, and dividing by 6,000.
Correct Answer Explanation: The nominal horsepower of a condensing engine is calculated using a specific formula: (diameter of the cylinder)^2 x piston speed / 6,000.
How is the actual horsepower of a steam engine calculated?
- Squaring the diameter of the cylinder, multiplying by the piston speed, and dividing by 6,000.
- Squaring the diameter of the cylinder, multiplying by the pressure (less 1.5 lbs for friction), and the piston speed, and dividing by 42,017.
- Multiplying the cylinder area by the piston speed and dividing by 33,000.
- Multiplying the cylinder area by the pressure and dividing by 33,000.
Correct Answer: Squaring the diameter of the cylinder, multiplying by the pressure (less 1.5 lbs for friction), and the piston speed, and dividing by 42,017.
Correct Answer Explanation: The actual horsepower of a steam engine is determined by accounting for the pressure and friction within the system.
What is the main advantage of working engines expansively?
- Increased speed
- Increased power
- Increased fuel efficiency
- Reduced wear and tear
Correct Answer: Increased fuel efficiency
Correct Answer Explanation: Working engines expansively allows for greater fuel efficiency. By allowing steam to expand after the steam valve is closed, more work is extracted from a given amount of steam, reducing fuel consumption.
What is the term for the amount of valve opening before the piston starts its stroke?
- Lead
- Lap
- Cutoff
- Expansion
Correct Answer: Lead
Correct Answer Explanation: Lead refers to the amount the steam valve is opened before the piston starts its stroke. This ensures that steam is already flowing into the cylinder when the piston begins its motion, leading to smoother operation and improved efficiency.
What is the approximate fire grate surface per nominal horsepower allowed by Boulton and Watt in their marine boilers?
- 0.32 square feet
- 0.48 square feet
- 0.64 square feet
- 0.80 square feet
Correct Answer: 0.64 square feet
Correct Answer Explanation: Boulton and Watt, prominent engineers of the Industrial Revolution, recommended a fire grate surface of 0.64 square feet per nominal horsepower in their marine boilers. This ensures adequate combustion and efficient steam generation.