GATE 2012 Mechanical Engineering (ME) Slot 1 - Offline Question Paper with Answer Key PDF (Feb-12-Forenoon Session)

GATE Questions

• 1.

  During a welding operation, thermal power of 2500 W is incident normally on a metallic surface. As shown in the figure below (figure is NOT to scale), the heated area is circular. Out of the incident power, 85% of the power is absorbed within a circle of radius 5 mm while 65% is absorbed within an inner concentric circle of radius 3 mm. The power density in the shaded area is _________ W mm^-2 (rounded off to 2 decimal places).

  

  
   

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• 2.

  Consider two infinitely long fins made of the same material and exposed to the same convective environment. One fin has a square cross-section of side \(a\), and the other has a circular cross-section of diameter \(d\). Assume \(a = d\). The ratio of the steady-state heat transfer rate from the square fin to that from the circular fin, \(\frac{\dot{Q}_{\text{square}}}{\dot{Q}_{\text{circular}}}\), is:

  • \(\frac{\pi}{4}\)
    
  • \(\frac{4}{\pi}\)
    
  • \(\frac{2}{\sqrt{\pi}}\)
    
  • \(\frac{\sqrt{\pi}}{2}\)
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• 3.

  A vibrating system has a critical damping coefficient \(C_c = 350 \, \text{N}\cdot\text{s/m}\) and an actual damping coefficient \(C = 35 \, \text{N}\cdot\text{s/m}\). The logarithmic decrement of the system is approximately:

  • 0.10
    
  • 0.31
    
  • 0.63
    
  • 3.14
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• 4.

  Two metal parts (a cylinder and a cube) of same volume are cast under identical conditions. The diameter of the cylinder is equal to its height. The ratio of the solidification time of the cube to that of the cylinder is _______________ (rounded off to 2 decimal places).
  Assume that solidification time follows Chvorinov's rule with an exponent of 2.
  

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• 5.

  A truss structure is loaded as shown in the figure below. Among the options given, which member in the truss is a zero-force member?

  

  \[ {Given: } F = 1000\,{N} \]

  • \(BD\)
    
  • \(BC\)
    
  • \(BA\)
    
  • \(AD\)
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• 6.

  For the differential equation given below, which one of the following options is correct? \[ \frac{\partial^2 u}{\partial x^2} + \frac{\partial^2 u}{\partial y^2} = 0, \quad 0 \leq x \leq 1, 0 \leq y \leq 1 \]

  • \( u = e^{x + y} \) is a solution for all \(x\) and \(y\)
    
  • \( u = e^{x} \sin y \) is a solution for all \(x\) and \(y\)
    
  • \( u = \sin x \sin y \) is a solution for all \(x\) and \(y\)
    
  • \( u = \cos x \cos y \) is a solution for all \(x\) and \(y\)
    
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