Mechanical Operations Mcqs

Q:

What is a conveyor?

A) A conveyor is a static equipment that is used to store heavy and bulky materials B) A conveyor is a moving equipment that is used to store heavy and bulky materials
C) A conveyor is a moving equipment that is used to carry heavy and bulky materials D) A conveyor is a moving equipment that is used to carry light and compact materials only
 
Answer & Explanation Answer: C) A conveyor is a moving equipment that is used to carry heavy and bulky materials

Explanation: A conveyor usually carries heavy and bulky material from one point of an industry to another. A conveyor can carry both light and heavy materials. A conveyor is not used for storage of any sort of materials, may it be heavy and bulky, or light.

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64
Q:

Which of the following is not of importance when a conveyor is designed?

A) Type of industry where the conveyor is being used B) Type of material being carried by the conveyor
C) Cost D) Length of travel of the conveyor
 
Answer & Explanation Answer: A) Type of industry where the conveyor is being used

Explanation: Any industry looks at its expenditure and wishes to maximize profit. The conveyor used shall be cost effective, therefore cost is an important element. The length of travel determines the amount of material to be used for its construction. In an industry several types of materials can be carried and the conveyor must be designed accordingly.

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182
Q:

Select the incorrect statement.

A) Drag depends inversely on mass B) Drag is independent of shape
C) Drag linearly depends on velocity D) Drag depends on compressibility
 
Answer & Explanation Answer: A) Drag depends inversely on mass

Explanation: Drag depends directly on the mass of the object. Several factors such as shape of the body, viscosity of fluid and lift experienced velocity of flow influence drag force. Drag is proportional to velocity in case of laminar flow however, it is proportional to the square of velocity in case of turbulent flow.

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29
Q:

Calculate the drag force on a ball of diameter of 80mm, flowing through air. The density of air is 1.25 kg/m³ and the ball flows with a velocity of 7m/s. The Reynolds number is 3730.

A) 0.077 N B) 76969 N
C) 0.011 N D) 10995 N
 
Answer & Explanation Answer: A) 0.077 N

Explanation: Not available for this question

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38
Q:

The total drag is a sum of the skin drag and the pressure drag. Which among of the following options, states the correct formula for skin drag and pressure drag?
(Here µ stands for dynamic viscosity of fluid, D stands for diameter of the sphere and U stands for velocity of flow of fluid.)

A) 2?µDU, 2?µDU B) 1?µDU, 2?µDU
C) 2?µDU, ?µDU D) 3?µDU, ?µDU
 
Answer & Explanation Answer: C) 2?µDU, ?µDU

Explanation: Total drag is accounted by two thirds of the skin drag and one third of the pressure drag. Skin drag, also called friction drag, is due to the friction offered by the fluid, while pressure drag is due to the pressure difference between the sides of the sphere.

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37
Q:

Under which circumstances is the Oseen formula valid for drag coefficient?

A) When the Reynolds number is between 0.3 and 5 B) When the Reynolds number is between 0.2 and 4
C) When the Reynolds number is between 0.3 and 4 D) When the Reynolds number is between 0.2 and 5
 
Answer & Explanation Answer: D) When the Reynolds number is between 0.2 and 5

Explanation: Not available for this question

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53
Q:

Under which condition, is the Cunningham correction factor applicable for very small particles?

A) When particle size is far greater than the gas mean free path B) When particle size is far lesser than the gas mean free path
C) When particle size becomes comparable to the gas mean free path D) Cunningham factor is applicable for small particles under all conditions
 
Answer & Explanation Answer: C) When particle size becomes comparable to the gas mean free path

Explanation: Slip occurs when particles have a comparable size with that of the gas mean free path and this is when the Cunningham factor is used. The total drag force, when divided by the Cunningham correction factor, gives an expression that accounts for the slip.

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31
Q:

Which of the following is not a disadvantage of Fluidized bed granulator?

A) A fluidized bed granulator cannot be efficiently used in a batch process B) A fluidized bed granulator has a long resident time
C) A fluidized bed granulator cannot be automated D) A fluidized bed granulator produces low density granules
 
Answer & Explanation Answer: C) A fluidized bed granulator cannot be automated

Explanation: A fluidized bed can be automated once the parameters are optimized and is one of the advantages of fluidized bed granulators. The low density granules are lighter due to lower gravity, and can get carried away easily. The residence time, which is the granulation period, also increases in a fluid bed granulator. A fluidized bed granulator cannot achieve the same degree of densification in batch mode as it does in continuous mode.

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