GATE ME topic:mechanics PYQs & Answers — Page 38

Questions 371–380 of 1040. Imported answers require independent review unless marked reviewed.

Topic practice 1040 questionsPage 38 of 104

A 4 mm thick aluminum sheet of width

mm is rolled in a two-roll mill of roll diameter 200 mm each. The workpiece is lubricated with a mineral oil, which gives a coefficient of friction,

. The flow stress (

) of the material in MPa is

, where

is the true strain. Assuming rolling to be a plane strain deformation process, the roll separation force (

) for maximum permissible draft (thickness reduction) is ________ kN (round off to the nearest integer).

Use:

where

is average flow stress,

is roll-workpiece contact length, and

is the average sheet thickness.

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The best size wire is fitted in a groove of a metric screw such that the wire touches the flanks of the thread on the pitch line as shown in the figure. The pitch (

) and included angle of the thread are 4 mm and 60°, respectively. The diameter of the best size wire is __________ mm (round off to 2 decimal places).

Diagram for Mechanical Engineering question 56

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Two mild steel plates of similar thickness, in butt-joint configuration, are welded by gas tungsten arc weld process using the following weld parameters.

Parameter	Value
Welding voltage	20 V
Welding current	150 A
Welding speed	5 mm/s

A filler wire of the same mild steel material having 3 mm diameter is used in this welding process. The filler wire feed rate is selected such that the final weld bead is composed of 60% volume of filler and 40% volume of plate material. The heat required to melt the mild steel material is 10 J/mm

. The heat transfer factor is 0.7 and melting factor is 0.6. The feed rate of the filler wire is ________ mm/s (round off to one decimal place).

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In a direct current arc welding process, the power source has an open circuit voltage of 100 V and short circuit current of 1000 A. Assume a linear relationship between voltage and current. The arc voltage (

) varies with the arc length (

) as

, where

is in volts and

is in mm. The maximum available arc power during the process is __________ kVA (in integer).

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An assignment problem is solved to minimize the total processing time of four jobs (1, 2, 3 and 4) on four different machines such that each job is processed exactly by one machine and each machine processes exactly one job. The minimum total processing time is found to be 500 minutes. Due to a change in design, the processing time of job 4 on each machine has increased by 20 minutes. The revised minimum total processing time will be __________ minutes (in integer).

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A cylindrical billet of 100 mm diameter and 100 mm length is extruded by a direct extrusion process to produce a bar of L-section. The cross sectional dimensions of this L-section bar are shown in the figure. The total extrusion pressure (

) in MPa for the above process is related to extrusion ratio (

) as

where

is the mean flow strength of the billet material in MPa,

is the portion of the billet length remaining to be extruded in mm,

is the initial diameter of the billet in mm, and

is the die shape factor.

If the mean flow strength of the billet material is 50 MPa and the die shape factor is 1.05, then the maximum force required at the start of extrusion is __________ kN (round off to one decimal place).

Diagram for Mechanical Engineering question 58

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The product structure diagram shows the number of different components required at each level to produce one unit of the final product P. If there are 50 units of on-hand inventory of component A, the number of additional units of component A needed to produce 10 units of product P is ________ (in integer).

Diagram for Mechanical Engineering question 59

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A project consists of five activities (A, B, C, D and E). The duration of each activity follows beta distribution. The three time estimates (in weeks) of each activity and immediate predecessor(s) are listed in the table. The expected time of the project completion is __________ weeks (in integer).

Activity	Optimistic time	Most likely time	Pessimistic time	Immediate predecessor(s)
A	4	5	6	None
B	1	3	5	A
C	1	2	3	A
D	2	4	6	C
E	3	4	5	B, D

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Consider a one-dimensional steady heat conduction process through a solid slab of thickness 0.1 m. The higher temperature side A has a surface temperature of 80 °C, and the heat transfer rate per unit area to low temperature side B is 4.5 kW/m

. The thermal conductivity of the slab is 15 W/m.K. The rate of entropy generation per unit area during the heat transfer process is ________ W/m

.K (round off to 2 decimal places).

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A rigid tank of volume of 8 m

is being filled up with air from a pipeline connected through a valve. Initially the valve is closed and the tank is assumed to be completely evacuated. The air pressure and temperature inside the pipeline are maintained at 600 kPa and 306 K, respectively. The filling of the tank begins by opening the valve and the process ends when the tank pressure is equal to the pipeline pressure. During the filling process, heat loss to the surrounding is 1000 kJ. The specific heats of air at constant pressure and at constant volume are 1.005 kJ/kg.K and 0.718 kJ/kg.K, respectively. Neglect changes in kinetic energy and potential energy.

The final temperature of the tank after the completion of the filling process is __________ K (round off to the nearest integer).

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GATE ME topic:mechanics PYQs

Question 56

Question 56

Question 57

Question 57

Question 58

Question 58

Question 59

Question 59

Question 60

Question 60