Mechanical GATE study

Replies

• 

  ISHAN TOPRE

  Here is my first set of doubts.
  Topic: metal castings
  
  What is the process used to keep the shape of the casting so that they remain uniform?
  
  1. The casting should be machined rough and kept in open place for months together.
  2. The casting should be hammered.
  3. The casting should be kept in a furnace.
  4. Loam sand should be put on the casting.
  
  How are the internal stresses of a casting removed?
  
  1. By machining off the hard and rigid outer skin.
  2. By polishing the casting.
  3. By making holes in the moulding box.
  4. By making one more gate in the loam sand (pattern sand)
  
  Why are the corners of a casting well rounded off by fillets?
  
  1. The corners are well rounded off because the casting becomes very weak at the corners.
  2. To get exact shape.
  3. To get extra thickness for the entire job shape.
  4. Because the job is having sharp corner shape.
  
  What is the approximate contraction per meter of cast iron while casting?
  
  1. 8 to 9 mm (1/120)
  2. 16 to 18mm (1/60)
  3. 13 mm (1/77)
  4. None of these
• 

  ISHAN TOPRE

  A machine working on a Carnot cycle operates between 305 K and 260 K. Determine the C.O.P. (Coefficient of Performance) when it is operated as
  
  1. 5.78, 6.78, 0.147
  2. 6.7, 5.78, 0.173
  3. 1.17, 12.5, 0.147
  4. none of the above
  
  A reservoir has been built 4 kilometers away from a college campus having 5,000 inhabitants. Water is to be supplied from the reservation to the campus. It is estimated that each inhabitant will consume 200 liters of water per day and half of the daily supply is pumped in 10 hours.
  If the loss of head due to friction in the pipe line is 20 m and assuming coefficient of friction for the pipe line as 0.008, what will be the diameter of the pipe?
  1. 20
  2. 18
  3. 36
  4. none of the above
  
  A town having population of 150,000 is to be supplied water from a reservoir 6.5 km away. It is stipulated that one half of the daily supply of 136 liters per head should be delivered in 8 hours. If the head availability is 15 m size of pipe.
  Take c = 80 for Chezy’s formula
  
  1. 56.4 cm
  2. 28.5 cm
  3. 66.8 cm
  4. None of the above
  
  An open rectangular tank accelerates up an inclined plane having inclination of 1 vertical to 4 horizontal as shown below:
  
  For the water surface to move from CE to CB, the acceleration of tank will be
  
  1. 1.98 m/s2
  2. 2.9 m/s2
  3. 2.3 m/s2
  4. None of the above
• 

  ISHAN TOPRE

  How to find rank of a matrix? Is there any simple method? a simple 3X3 matrix or a harder one 4X4 matrix? anyone has idea?
• 

  maria flor

  You can use calculator for a 3x3 matrix....
• 

  ISHAN TOPRE

  Yeah calculator is a good option but we cannot find rank of matrix, we can merely find determinant and perform other operations.
  Finding manually rather than calculator would be an easy technique for rank.
  
  I have Casio 991ES
• 

  maria flor

  okie...as far as i know Casio 991ES or Casio 991ES+other can't be use here during Board exams because it's programmable... so I'm using 991MS😔
• 

  yadavundertaker mohit

  for finding the rank of the matrix try to make last column all zeros...when you will not make more zeros then the maximum square matrix which can be made is know as rank of the matrix..
• 

  ISHAN TOPRE

  My question here today refers to the cutting tools.
  
  Which is equation is commonly used for a lathe machine?
  
  one is V=(257/60[SUP]0.19[/SUP]XS[SUP]0.36[/SUP]Xt[SUP]0.08[/SUP])
  Where V is the speed of cutting in mm/min
  S is feed in mm/min and t is depth of cut in mm.
  
  And other is VT[SUP]n[/SUP]=C
  
  Where T is tool life and n,C are constants. The rest things are similar
• 

  ShrinkDWorld

  ishutopre

  Here is my first set of doubts.
  Topic: metal castings
  
  What is the process used to keep the shape of the casting so that they remain uniform?
  
  1. The casting should be machined rough and kept in open place for months together.
  2. The casting should be hammered.
  3. The casting should be kept in a furnace.
  4. Loam sand should be put on the casting.
  
  How are the internal stresses of a casting removed?
  
  1. By machining off the hard and rigid outer skin.
  2. By polishing the casting.
  3. By making holes in the moulding box.
  4. By making one more gate in the loam sand (pattern sand)
  
  Why are the corners of a casting well rounded off by fillets?
  
  1. The corners are well rounded off because the casting becomes very weak at the corners.
  2. To get exact shape.
  3. To get extra thickness for the entire job shape.
  4. Because the job is having sharp corner shape.
  
  What is the approximate contraction per meter of cast iron while casting?
  
  1. 8 to 9 mm (1/120)
  2. 16 to 18mm (1/60)
  3. 13 mm (1/77)
  4. None of these

  My answers are-->
  1] 4. Loam sand should be put on the casting.
  2] 3. By making holes in the moulding box.
  3] 1. The corners are well rounded off because the casting becomes very weak at the corners.
  4] 1. 8 to 9 mm
  please post correct answers.
• 

  ShrinkDWorld

  ishutopre

  My question here today refers to the cutting tools.
  
  Which is equation is commonly used for a lathe machine?
  
  one is V=(257/60[SUP]0.19[/SUP]XS[SUP]0.36[/SUP]Xt[SUP]0.08[/SUP])
  Where V is the speed of cutting in mm/min
  S is feed in mm/min and t is depth of cut in mm.
  
  And other is VT[SUP]n[/SUP]=C
  
  Where T is tool life and n,C are constants. The rest things are similar

  second equation is correct. i am sure for second option.
  But i think both of above equations are used for calculating tool life. but i am not sure for first one.
  please correct me.
• 

  Tapan_mech

  #-Link-Snipped-##-Link-Snipped-#
  
  
  Hi , I have a doubt from Strength of Material posted in the above link. would request to please clarify the doubt!
• 

  jigarmech

  Issue

  
  An open rectangular tank accelerates up an inclined plane having inclination of 1 vertical to 4 horizontal as shown below:
  
  For the water surface to move from CE to CB, the acceleration of tank will be
  
  1. 1.98 m/s2
  2. 2.9 m/s2
  3. 2.3 m/s2
  4. None of the above

  can any one tell me the how to find this?
• 

  ISHAN TOPRE

  Check out post #10 #-Link-Snipped-# If you face any difficulty, feel free to ask.
• 

  jigarmech

  thnx...
• 

  jigarmech

  Issue

  Check out post #10 #-Link-Snipped-# If you face any difficulty, feel free to ask.

  i am still a bit confused...
  how will i find the volume of water displaced?
• 

  ISHAN TOPRE

  The water represented by the outside triangle will be water spilled. Multiply area of that triangle with width. It is easy. Have you tried it by taking pencil and paper?
• 

  jigarmech

  
  
  which triangle? triangle CEB?
• 

  ISHAN TOPRE

  What are you doing man? the question itself is wrong. click on the link and look for post #10. I have explained similar type of problem 😀
  Check for the upper triangle there.
  #-Link-Snipped-#