UPPSC Lec’21 ME: Daily Practices Quiz. 19-Nov-2021

Quiz: Mechanical Engineering
Exam: UPPSC AE/Lecturer
Topic: Power Plant

Each question carries 3 marks
Negative marking: 1 mark
Time: 8 Minutes

Q1. A fixed gear which has 100 teeth, is in mesh with another gear which has 50 teeth. It is given that the two gears are connected by an arm. The number of turns made by the smaller gear for one revolution of arm about the centre of the bigger gear is
(a) 2
(b) 3
(c) 4
(d) 6

Q2. Consider the following statements:
The pressure angle of pinion is 14 ½ °, and the number of involute teeth is 48 which have pitch circle diameter of 28.8 cm. Which of the following statement is correct?
1. module of 6 mm
2. circular pitch of 18 mm
3. addendum of 6 mm
4. diametral pitch of 11/113
Which of these statements are correct?
(a) 2 and 3
(b) 1 and 3
(c) 1 and 4
(d) 2 and 4

Q3. The gear profile which satisfies the law of gearing are
1. Involute profiles
2. Cycloidal profiles
3. Conjugate profiles
(a) 1 and 2 only
(b) 1 and 3 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q4. Pressure angle of involute gears does not exceed 25°, since
(a) this will lead to unwanted radial force
(b) the number of teeth to avoid undercutting will be very high
(c) no cutters are available
(d) gears will become too small

Q5. The minimum number of links in a constrained planer mechanism involving revolute pairs and two higher pairs is:
(a) 3
(b) 4
(c) 5
(d) 6

Q6. The total number of instantaneous centres for a mechanism consisting of ‘6’ links is
(a) 3
(b) 6
(c) 30
(d) 15

Solutions

S1. Ans.(b)
Sol.
The speed table of the gear system is as follows

S2. Ans.(b)
Sol. Given that, θ = 14.5° Z = 48, d = 288 mm
Module = d/z = 288/48 = 6 mm
Circular pitch = πm = 6π = 18.85 mm
addendum = m = 6 mm
diametral pitch = 1/m = 1/6

S3. Ans.(d)
Sol. Law of gearing: When teeth of two gears are in contact the common normal at the point of contact cuts the line joining the centre of two gears at a point which divides it in the inverse ratio of their angular velocity.

S4. Ans.(a)
Sol. Pressure angle of involute gears does not exceed 25°, since this will lead to unwanted radial force.

S5. Ans.(d)
Sol. The minimum number of links in a constrained planer mechanism with revolute pairs and two higher pairs is 6.

S6. Ans.(d)
Sol. Total No. of I.C. = n(n-1)/2=(6×5)/2=15

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