GATE 2021 ME (Set 1) question paper PDF and answer key

The official GATE 2021 Mechanical Engineering (Set 1) paper, organised by IIT Bombay: 65 questions for 100 marks in 3 hours. Download the official question paper and answer key as PDFs. Below is how the marks were split by topic, the complete official answer key and 5 questions solved step by step.

Source: the official paper and answer key published by IIT Bombay for GATE 2021 (official GATE site). Spotted a mistake? Email team@lemyte.com.

General Aptitude
10 · 15 marks
Mechanical Engineering
55 · 85 marks
MCQ / MSQ / NAT
38 / 0 / 27
Marks to all
None

Not in 2027 1 question (Q 23) is on topics removed from the GATE 2027 syllabus. They are marked in the answer key below. What changed for ME

Where the marks were

GATE 2021 ME (Set 1) topic-wise marks

Mechanical Engineering questions only; General Aptitude adds 15 marks on top. The top three topics carried 32 of the 85 subject marks.

TopicQuestionsMarks
Manufacturing Engineering1016
Thermodynamics69
Mechanics of Materials57
Machine Design47
Industrial Engineering47
Heat Transfer46
Fluid Mechanics46
Vibrations35
Theory of Machines34
Calculus23
Probability and Statistics23
Thermal Applications23
Differential Equations22
Linear Algebra12
Complex Variables12
Applied Mechanics12
Numerical Methods11

Free solved questions

5 solved questions from GATE 2021 ME (Set 1)

Question text and figures as in the official paper, the answer from the official key, and a worked solution. The other 60 solutions are in your report after you take the paper.

Q2 · General Aptitude · MCQ · 1 mark

Ms. X came out of a building through its front door to find her shadow due to the morning sun falling to her right side with the building to her back. From this, it can be inferred that building is facing _________

  • (A)
    North
  • (B)
    East
  • (C)
    West
  • (D)
    South

Answer (official key): D

Solution

The morning sun is in the east, so her shadow falls towards the west. West is to her right when she faces south. Since the building is behind her, its front faces South (D).

Q10 · General Aptitude · MCQ · 2 marks

Five persons P, Q, R, S and T are sitting in a row not necessarily in the same order. Q and R are separated by one person, and S should not be seated adjacent to Q.

The number of distinct seating arrangements possible is:

  • (A)
    44
  • (B)
    88
  • (C)
    1010
  • (D)
    1616

Answer (official key): D

Solution

Number seats 11 to 55. The possible ordered positions (Q,R)(Q,R) are (1,3),(3,1),(2,4),(4,2),(3,5),(5,3)(1,3),(3,1),(2,4),(4,2),(3,5),(5,3). These leave respectively 2,1,1,1,1,22,1,1,1,1,2 allowed positions for S. P and T can occupy the remaining seats in 2!2! ways. Total =(2+1+1+1+1+2)2=16=(2+1+1+1+1+2)2=16. Answer: D.

Q53 · Heat Transfer · Numerical · 2 marks

An uninsulated cylindrical wire of radius 1.0 mm1.0\ \mathrm{mm} produces electric heating at the rate of 5.0 W/m5.0\ \mathrm{W/m}. The temperature of the surface of the wire is 75 ∘C75\ ^\circ\mathrm{C} when placed in air at 25 ∘C25\ ^\circ\mathrm{C}. When the wire is coated with PVC of thickness 1.0 mm1.0\ \mathrm{mm}, the temperature of the surface of the wire reduces to 55 ∘C55\ ^\circ\mathrm{C}. Assume that the heat generation rate from the wire and the convective heat transfer coefficient are same for both uninsulated wire and the coated wire. The thermal conductivity of PVC is __________ W/(m K)\mathrm{W/(m\,K)} (round off to two decimal places).

Answer (official key): 0.1 to 0.12

Solution

For the bare wire, h=5/[2π(0.001)(75−25)]=15.915 W/(m2K)h=5/[2\pi(0.001)(75-25)]=15.915\ \mathrm{W/(m^2K)}. For the coated wire, (55−25)/5=ln⁡(0.002/0.001)/(2πk)+1/[2π(0.002)h](55-25)/5=\ln(0.002/0.001)/(2\pi k)+1/[2\pi(0.002)h]. Hence 6=ln⁡2/(2πk)+56=\ln2/(2\pi k)+5, giving k=ln⁡2/(2π)=0.11 W/(m K)k=\ln2/(2\pi)=\boxed{0.11\ \mathrm{W/(m\,K)}}.

Q54 · Heat Transfer · Numerical · 2 marks

A solid sphere of radius 10 mm10\ \mathrm{mm} is placed at the centroid of a hollow cubical enclosure of side length 30 mm30\ \mathrm{mm}. The outer surface of the sphere is denoted by 11 and the inner surface of the cube is denoted by 22. The view factor F22F_{22} for radiation heat transfer is __________ (rounded off to two decimal places).

Answer (official key): 0.76 to 0.78

Solution

The sphere is convex, so F11=0F_{11}=0 and F12=1F_{12}=1. Reciprocity gives F21=A1/A2=4π(10)2/[6(30)2]=0.23271F_{21}=A_1/A_2=4\pi(10)^2/[6(30)^2]=0.23271. Therefore F22=1−F21=0.77F_{22}=1-F_{21}=\boxed{0.77}.

Q57 · Fluid Mechanics · Numerical · 2 marks

A cylindrical jet of water (density =1000 kg/m3=1000\ \mathrm{kg/m^3}) impinges at the center of a flat, circular plate and spreads radially outwards, as shown in the figure. The plate is resting on a linear spring with a spring constant k=1 kN/mk=1\ \mathrm{kN/m}. The incoming jet diameter is D=1 cmD=1\ \mathrm{cm}.

Figure for GATE 2021 ME (Set 1) question 57 (Fluid Mechanics)

If the spring shows a steady deflection of 1 cm1\ \mathrm{cm} upon impingement of jet, then the velocity of the incoming jet is __________ m/s\mathrm{m/s} (round off to one decimal place).

Answer (official key): 11.2 to 11.4

Solution

The jet force is ρAV2\rho AV^2, since the outgoing flow has no vertical velocity. Equating this to spring force gives 1000[π(0.01)2/4]V2=1000(0.01)=101000[\pi(0.01)^2/4]V^2=1000(0.01)=10. Thus V=11.3 m/sV=\boxed{11.3\ \mathrm{m/s}}.

The other 60 questions are solved in your report when you take GATE 2021 ME (Set 1) as a 3-hour test.

Take GATE 2021 ME (Set 1) as a test

Official answer key

GATE 2021 ME (Set 1) answer key

All 65 answers from the official key. Numerical answers are ranges; “or” means the key accepts either answer.

Download the official GATE 2021 ME (Set 1) answer key (PDF)
QTopicTypeMarksAnswer
1Verbal AptitudeMCQ1D
2Analytical AptitudeMCQ1D
3Quantitative AptitudeMCQ1D
4Quantitative AptitudeMCQ1D
5Verbal AptitudeMCQ1C
6Verbal AptitudeMCQ2C
7Spatial AptitudeMCQ2A
8Quantitative AptitudeMCQ2C
9Quantitative AptitudeMCQ2C
10Analytical AptitudeMCQ2D
11Differential EquationsMCQ1C
12CalculusMCQ1C
13Differential EquationsMCQ1D
14Numerical MethodsMCQ1A
15Probability and StatisticsMCQ1D
16Mechanics of MaterialsMCQ1B
17Manufacturing EngineeringMCQ1B
18Manufacturing EngineeringMCQ1A
19Manufacturing EngineeringMCQ1A
20Manufacturing EngineeringMCQ1B
21ThermodynamicsMCQ1B
22ThermodynamicsMCQ1C
23Heat TransferNot in GATE 2027 syllabus: Heisler's chartsMCQ1A
24Heat TransferMCQ1A
25Thermal ApplicationsMCQ1A
26Theory of MachinesMCQ1C
27Mechanics of MaterialsMCQ1C
28Mechanics of MaterialsMCQ1D
29Machine DesignMCQ1C
30Industrial EngineeringNumerical1331 to 333
31Fluid MechanicsNumerical1397 to 399
32Fluid MechanicsNumerical179 to 81
33ThermodynamicsNumerical1555 to 565
34Theory of MachinesNumerical10
35VibrationsNumerical10.085 to 0.09
36Linear AlgebraMCQ2B
37Complex VariablesMCQ2C
38Industrial EngineeringMCQ2A
39ThermodynamicsMCQ2B
40VibrationsMCQ2B
41Mechanics of MaterialsMCQ2A
42VibrationsMCQ2B
43Probability and StatisticsMCQ2A
44CalculusMCQ2C
45Industrial EngineeringNumerical20.5
46Manufacturing EngineeringNumerical2660 to 664
47Manufacturing EngineeringNumerical230 to 36
48Manufacturing EngineeringNumerical2625 to 750
49Manufacturing EngineeringNumerical245 to 50
50Manufacturing EngineeringNumerical2775 to 784
51Manufacturing EngineeringNumerical20.2 to 0.3
52Industrial EngineeringNumerical24
53Heat TransferNumerical20.1 to 0.12
54Heat TransferNumerical20.76 to 0.78
55Thermal ApplicationsNumerical292 to 96
56ThermodynamicsNumerical2195.1 to 195.3
57Fluid MechanicsNumerical211.2 to 11.4
58Fluid MechanicsNumerical22.5 to 2.8
59ThermodynamicsNumerical24.9 to 5.1
60Applied MechanicsNumerical2124 to 126
61Mechanics of MaterialsNumerical2249 to 251
62Theory of MachinesNumerical21.9 to 2.1
63Machine DesignNumerical2199 to 201
64Machine DesignNumerical21.9 to 2.1
65Machine DesignNumerical26.4 to 6.9

Questions about GATE 2021 ME (Set 1)

How many questions are in the GATE 2021 ME (Set 1) paper?

65 questions for 100 marks: 10 General Aptitude questions worth 15 marks and 55 Mechanical Engineering questions worth 85 marks. By type, there were 38 MCQs, 27 numerical answer (NAT) questions. The paper lasted 3 hours.

Is there negative marking in GATE 2021 ME (Set 1)?

Yes, for MCQs only. A wrong MCQ answer costs one-third of its marks (−⅓ for a 1-mark question, −⅔ for a 2-mark question). MSQ and numerical (NAT) questions have no negative marking, and an MSQ earns marks only when every correct option is chosen.

Which topics carried the most marks in GATE 2021 ME (Set 1)?

Outside General Aptitude, the biggest topics were Manufacturing Engineering (16 marks), Thermodynamics (9 marks), Mechanics of Materials (7 marks). The full topic-wise split is in the table on this page.

Were any GATE 2021 ME (Set 1) questions awarded marks to all?

No. Every question was graded with the answer in the official key.

Where does this GATE 2021 ME (Set 1) answer key come from?

From the official answer key published by IIT Bombay, which organised GATE 2021. Range answers for numerical questions and questions with more than one accepted answer are kept exactly as the key gives them.

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