Important ESE Mechanical Engineering

1. A rotor weighing 2 kN is supported on bearings A and B which are 1 m apart. The centre of mass of the rotor is at a distance 0.4 m from bearing A. It is observed that there is an unbalanced couple of magnitude 300 N-m which *leaves the shaft balanced statically. The dynamic reactions at the supports will be
(a) 800 N and 800 N
(b) 300 N and 800 N
(c) 800 N and –300 N
(d) 300 N and –300 N
Ans. (d)
2. . A cam is a mechanical member used to impart a desired motion to a follower by direct contact. Which one of the under-listed follower motion types will produce the least jerk to the system?
(a) Simple harmonic
(b) Constant acceleration and deceleration
(c) Constant velocity
(d) Cycloidal
Ans. (d)
3.In a circular are cam with a roller follower, acceleration of the follower depends on
1. cam speed and location of centre of circular arc
2. roller diameter and radius of circular arc
Which of the above is/are correct?
(a) 1 only                     
(b) 2 only
(c) Both 1 and 2           
(d) Neither 1 nor 2
Ans. (c)
4. A manufacturing company is selling a product for 15 per unit with variable cost of  10 per unit. The fixed cost of the asset is 50,000. How many units should be produced to breakeven?
(a) 2000                       
(b) 5000
(c) 8000                        
(d) 10000
Ans. (d)

5. In a crank and slotted lever quick return motion mechanism, the distance between the fixed centres is 200 mm. The lengths of the driving crank and the slotted bar are 100 mm and 500 mm, respectively. The length of the cutting stroke is
(a) 100 mm                   
(b) 300 mm
(c) 500 mm                   
(d) 700 mm
Ans. (c)

6. A gear of 28 cm pitch circle diameter has 40 teeth. The circular pitch will nearly be
(a) 11 mm/tooth            
(b) 22 mm/tooth
(c) 33 mm/tooth            
(d) 44 mm/tooth
Ans. (b)

7. The flywheel of a steam engine has a radius of gyration of 1 m and mass 2000 kg. The starting torque of the engine is 2000 N-m. The kinetic energy of the flywheel after 10 seconds from start is
(a) 75 kN-m                  
(b) 100 kN-m
(c) 125 kN-m                
(d) 150 kN-m
Ans. (b)
8. A riveting machine is driven by a constant-torque 3 kW motor. The moving parts including the flywheel are equivalent to 150 kg at 0.6 m radius. One riveting operation takes 1 second and absorbs 10000 N-m of energy. The speed of the flywheel is 300 r.p.m. before riveting. What is the speed (to nearest 10 r.p.m.) after riveting and what is the number of rivets that can be closed per minute?
(a) 260 r.p.m. and 18    
(b) 290 r.p.m. and 15
(c) 360 r.p.m. and 18    
(d) 390 r.p.m. and 15
Ans. (a)
9. The thickness of the continuous weld used for connecting a horizontal square bar of 150 mm size and of cantilevered length 500 mm to a vertical plate, with the bar carrying a 25 kN vertical load at its outer tip, given that the permissible direct shear stress of the weld is 20 N/mm2, is
(a) 3 mm                      
(b) 4 mm
(c) 5 mm                      
(d) 6 mm
Ans. (a)
10. A shaft of 50 mm diameter transmits a torque of 800 N-m. The width of the rectangular key used is 10 mm. The allowable shear stress of the material of the key being 40 MPa, the required length of the key would be
(a) 60 mm                    
(b) 70 mm
(c) 80 mm                    
(d) 90 mm
Ans. (c)
For More Important ESE Mechanical Engineering  - Click Here