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# Mechanical Operations MCQ’s – Mechanism of Size Reduction

In the below equation, When n=1 it yields?

a) Kick’s law

b) Bond’s law

c) Rittingers law

d) Bose equation

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Answer: a

Explanation: when we substitute n = 1, in the above equation we get an integral form of equation, which then integrated over a and b yield kick’s law.

The below equation hold true for ____

a) Kick’s law

b) Rittingers law

c) James law

d) Camp law

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Answer: b

Explanation: when we substitute n = 1, in the above equation we get the Rittingers law equation over the particle size D_{sa} and D_{sb}.

On which of the following, K_{f} and K_{k} depends?

a) Type of machine

b) Type of power

c) Type of operation

d) Type of law

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Answer: a

Explanation: Both Kick’s and Rittingers law is applied over a limited range of the particles size, hence K_{f} and K_{k} depend upon type of machine.

The most accurate law for estimating the power is ____

a) Rittingers law

b) Bond’s law

c) Kick’s law

d) Power law

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Answer: b

Explanation: Bond’s law is more realistic for estimating the power required for the crushing and grinding operations of any kind.

According to Bond, the work required is proportional to ____

a) Surface to volume ratio

b) Square of surface to volume ratio

c) Square root of surface to volume ratio

d) New surface area created

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Answer: c

Explanation: The Bond law states that the work required to form a particle of size Dp from a very large feed is proportional to square root of surface to volume ratio.

What is the surface to volume ratio?

a) S_{p}/D_{p}

b) S_{p}/V_{p}

c) D_{p}/V_{p}

d) D_{p}/K_{p}

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Answer: b

Explanation: The surface to volume ratio is given as S_{p}/V_{p}, where S_{p} is surface area and V_{p} is the volume of the feed.

What does the below equation represents?

a) Bond’s law

b) Kick’s law

c) Rittingers law

d) Camp law

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Answer: a

Explanation: The above equation represents the Bond’s law, where P is the power required and m is the mass of the feed and K_{b} is the Bond’s constant.

On which of the following, K_{b} depends?

a) Type of machine and material

b) Type of power

c) Type of operation

d) Type of law

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Answer: a

Explanation: According to Bond’s law, the Bond’s constant K_{b} depends upon the type of machinery used and the type of feed applied.

In below equation, what value of n yields Bond’s law?

a) 0

b) 0.5

c) 1.5

d) 1

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Answer: c

Explanation: The generalized differential equation when equated n equals to 1.5 yields the Bond’s law in particular.

The gross energy requirement is called as ____

a) Work index

b) Power index

c) Energy index

d) Final index

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Answer: a

Explanation: Wi or Work index is defined as the gross energy requirement in kilowatt hours per unit ton of feed needed to reduce very large feed to 80%.