# MCQs on Coefficient of Flywheel

Calculate the coefficient of fluctuation of speed if maximum speed is 2500rpm and minimum speed is 1800rpm.

a) 1.44

b) 1.33

c) 0.33

d) 0.44

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Answer: c

Explanation: C=2[(Max-Min)/(Max+Min)].

Calculate the coefficient of steadiness if maximum speed of flywheel is 2500rpm and minimum speed is 1800rpm.

a) 3.03

b) 0.33

c) 0.44

d) 3.99

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Answer: a

Explanation: C=1.Coeffecient of fluctuation of speed.

Figure1 Answer the questions 3-7 with respect to figure1. Calculate the mean torque T supplied by motor (Torque vs. theta graph of a flywheel is shown above).

a) 3000N-m

b) 1500N-m

c) 2000N-m

d) 2500N-m

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Answer: b

Explanation: T[1000+2000/2]x2π/2π.

The point where angular velocity is maximum is?

a) A

b) B

c) C

d) D

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Answer: c

Explanation: The flywheel is decelerated in the portion BC and hence rpm is least at C.

The point where velocity of flywheel is maximum is

a) A

b) B

c) C

d) D

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Answer: b

Explanation: Flywheel is accelerated in the portion AB and hence velocity is maximum at B

Calculate the energy output from flywheel.

a) 500π

b) 150π

c) 200π

d) 250π

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Answer: d

Explanation: U=Area of ΔBCD as max and min velocities are at B and C.

Torque vs. theta graph of a flywheel is shown. Coefficient of fluctuation of speed is 0.2 and the mean angular velocity of the machine is 25 rad/s. Thickness of flywheel is 20mm and density of steel used is 7700kg/mᵌ. Calculate the outer radius of the flywheel.

a) 402mm

b) 202mm

c) 540mm

d) 468mm

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Answer: a

Explanation: I=U/ω²C and I=πptR⁴/2.

Figure 2 The turning moment diagram of a multi cylinder engine is shown. The intercepted areas between torque developed by the engine and the mean resisting torque of the machine taken in order from one end are -300,+850 -500, + 900, -550, + 430 and -700 mm². Answer questions 8-13 with respect to figure 2 Calculate the energy at point B if energy assumed at point A is U.

a) U

b) U-300

c) U+300

d) U-150

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Answer: b

Explanation: Simple addition of energy.

Calculate the energy at point C if energy at point A is U.

a) U-550

b) None of the listed

c) U+550

d) U+550

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Answer: c

Explanation: E=U-300+ 850.

Calculate the energy at point F if energy at A is u.

a) U+340

b) U+260

c) U+400

d) Can’t be determined

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Answer: c

Explanation: E=U-300+850-500+900-550.

Calculate the maximum energy.

a) U+1000

b) U+950

c) U+630

d) U+600

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Answer: b

Explanation: Maximum energy is at E. E=U-300+850-500+900.

Calculate the point of minimum energy.

a) U+480

b) U+650

c) U-300

d) U-450

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Answer: c

Explanation: Minimum energy is at B. E=U-300.

Calculate the net energy output from the flywheel.

a) 1300mm²

b) 1400mm²

c) 1250mm²

d) 1500mm²

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Answer: c

Explanation: Maximum energy at E[U+950] and minimum at B[U-300]. Thus net energy=[U+950]-[U-300].

Feather key can be used to prevent axial motion between two elements.

a) True

b) False

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Answer: bExplanation: All types of key but feather key can be used to prevent axial motion between two machine elements.

Keyed joints never lead to stress concentration on shafts.

a) True

b) False

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Answer: b

Explanation: Keyway results in stress concentration in the shaft and makes the part weak.