  # ISRO Scientist or Engineer Mechanical 2020

Instructions

For the following questions answer them individually

Question 61

# A cylindrical pressure vessel has diameter 200 mm and thickness 9 mm. Find the hoop and axial stress $$(\frac{N}{mm^{2}})$$ in the cylindrical vessel, when it is subjected to an internal pressure of 5 MPa. Question 62

# For a long slender columnof uniform cross section, the ratio of critical buckling load for the case with both ends hingedto the case with both ends clampedis Question 63

# If the length of a column subjected to compressive load is increased by three times its original length, the critical buckling load becomes Question 64

# A squarebar of size $$10mm \times 10 mm$$ and length 1000 mmis subjected to 200 N axialtensile force. The bar is made of mild steel having modulusofelasticity of 200 GPa. Find the strain energy density stored in the bar underthis state of loading? Question 65

# A solid circular shaft needs to be designed to transmit a torque of 55 N m. If the allowable shearstress of the material is 280 $$\frac{N}{mm^{2}}$$ ind the diameter (in mm)of the shaft required tO transmit the torque. $$(Assume,\pi=\frac{22}{7})$$ Question 66

# If S is the applied stress, c 1s the width of the crack and r the radius of curvature at the tip of the crack, Griffith's crack theory gives the concentrated stress $$S_{c}$$ as Question 67

# A metal alloy machine component is subjected to fluctuating tensile stress from 100 $$\frac{N}{mm^{2}}$$ to 200 $$\frac{N}{mm^{2}}$$. The material has yield and endurance strength of 450 and 200 $$\frac{N}{mm^{2}}$$ respectively. Find the factor of safety of the machine component. Question 68

# A diver of mass 100kg is standing at the tip of a spring board of negligible mass. The natural frequency of the spring board with the diver is 1.6Hz. Whatis the static deflection at the tip of the spring board whenthe diveris standing at the tip? Question 69

# Which of the followingis classified as a secondary bondin materials? Question 70

# The numberof atoms per unit cell for an FCC crystal structure is OR