MOST EXPECTED QUESTIONS IN ENGG MECHANICS
State and prove perpendicular axis theorem for moment of inertia.
State and prove parallel axis theorem
Derive expression for centroid of triangular area of base (B) and height (H)
State laws of static and dynamic friction
Define the terms centroid and moment of inertia
Define the trems centroid and moment of inertia
Write short notes on
Radius of gyration
Product of inertia
Define angle of friction and angle of repose and prove that fro limiting condition both are equal.
Prepare numericals for CG and MI, for shapes as asked in las year’s papers.
Discuss advantages of method of sections for analysis of trusses. Write steps for solving trusses by method of sections.
What is meant by principle of virtual work.
State Assumptions made in analysis of a plane truss
Explain
Law of machine
Self locking machine
Velocity ratio
Explain with sketches simple and compound gear trains
Define and differentiate between initial tension and centrifugal tension in a belt drive
Find condition of irreversibility of a machine
Enumerate merits of rope drive over belt drive
Enumerate the advantages of gear drives over belt and rope drives
Explain the law of machine
Prove that the condition for self locking machine is that its efficiency is less than 50%
Prepare numericals for Belt drive, all types as asked in lasy year’s papers ( keep special watch on unit conversions and formulas to be used)
Prove relation ship T1/T2 = eμθ
Deduce relationship between SF and BM.
Prepare BM and SF numericals specially for Overhang cases and simply supported cases
State and explain principle of moments
Same material is also available on http://www.studypages.blogspot.com/State and prove Varignon’s theorem. Explain its application in non concurrent forces
Sunday, January 13, 2008
Wednesday, January 2, 2008
BCE practical Viva Questions
Expected Common Questions for Viva BCE Practical Exam:
What is basic principle of chain surveying.
What is the purpose of providing metal tags at different places in a chain.
What is ranging. Why is it done.
What are perpendicular offsets.
What are oblique offsets.
Name the different types of magnetic compass.
What is difference between Prismatic and Surveyor’s compass.
What is Whole circle bearing system, what is the max. value of bearing in WCB.
What is Quadrantal or reduced bearing, what is the max. value of bearing in QB.
What is local attraction.
What should be difference between Fore bearing and back bearing.
What is the least count of a leveling scale.
Show various parts of a dumpy level in the diagram.
What are temporary adjustments in dumpy level.
What is difference between “HI” method and “Rise and fall” method of leveling.
Which method is faster between the two.
Which method has lesser chances of errors between the two.
What is difference between Dumpy level and Theodolite
What are the temporary adjustments of theodolite.
Explain the figure in notebook showing scheme of finding height of building using trigonometric leveling.
Can a theodolite be used as a dumpy level, If yes what adjustment has to be done before using it as dumpy level.
What are advantages of plane table survey over normally used other survey techniques.
What are disadvantages of plane table survey over normally used other survey techniques.
What is the use of alidade in plane tabling
What is orientation of plane table.
In which type of areas do we apply radiation method.
In which type of areas do we apply intersection method.
What is bulking of sand
Explain the mechanism of sand bulking
What is the relationship of bulking with particle size of sand.
What is concrete
What is workability of concrete
How is workability of concrete measured in field.
What should be the normal value of slump for concrete in general use.
What is use of Vicat’s apparatus
What is Initial setting time of cement
What is final setting time of cement
What are the limits as per IS code for IST and FST of OPC.
What are the different types of cement available in market.
What are the general IS codes used for Civil engineering purpose.
Best of luck - Sanjay Saini
What is basic principle of chain surveying.
What is the purpose of providing metal tags at different places in a chain.
What is ranging. Why is it done.
What are perpendicular offsets.
What are oblique offsets.
Name the different types of magnetic compass.
What is difference between Prismatic and Surveyor’s compass.
What is Whole circle bearing system, what is the max. value of bearing in WCB.
What is Quadrantal or reduced bearing, what is the max. value of bearing in QB.
What is local attraction.
What should be difference between Fore bearing and back bearing.
What is the least count of a leveling scale.
Show various parts of a dumpy level in the diagram.
What are temporary adjustments in dumpy level.
What is difference between “HI” method and “Rise and fall” method of leveling.
Which method is faster between the two.
Which method has lesser chances of errors between the two.
What is difference between Dumpy level and Theodolite
What are the temporary adjustments of theodolite.
Explain the figure in notebook showing scheme of finding height of building using trigonometric leveling.
Can a theodolite be used as a dumpy level, If yes what adjustment has to be done before using it as dumpy level.
What are advantages of plane table survey over normally used other survey techniques.
What are disadvantages of plane table survey over normally used other survey techniques.
What is the use of alidade in plane tabling
What is orientation of plane table.
In which type of areas do we apply radiation method.
In which type of areas do we apply intersection method.
What is bulking of sand
Explain the mechanism of sand bulking
What is the relationship of bulking with particle size of sand.
What is concrete
What is workability of concrete
How is workability of concrete measured in field.
What should be the normal value of slump for concrete in general use.
What is use of Vicat’s apparatus
What is Initial setting time of cement
What is final setting time of cement
What are the limits as per IS code for IST and FST of OPC.
What are the different types of cement available in market.
What are the general IS codes used for Civil engineering purpose.
Best of luck - Sanjay Saini
Tuesday, December 25, 2007
Numericals Belt drive and lifting M/c
Engg Mechanics - Numerical Examples
Belt Drive and Lifting machines
A belt 100mm wide and 8mm thick is transmitting power of a belt of speed of 1600m/minute. The angle of lap for the smaller pulley is 165 deg. And the coefficient of friction is 0.3. The maximum permissible stress in belt is 2MN/sq.m. and the mass of belt is 0.9 kg/m. find the power transmitted and the initial tension in the belt.
An open belt running over two pulleys 1.5m and 1.0m diameter connects two parallel shafts 4.80m apart. The initial tension in the belt when stationary is 3000N. If the smaller pulley is rotating at 600 rpm and coefficient of friction between the belt and pulley is 0.3. Determine the power transmitted taking centrifugal tension into account. The mass of the belt is given as 0.6703 kg/m length.
A belt 200mm wide and 8mm thick is transmitting power of a belt of speed of 1700m/minute. The angle of lap for the smaller pulley is 165 deg. And the coefficient of friction is 0.25. The maximum permissible stress in belt is 2500 KN/sq.m. and the mass of belt is 10 KN/cubic m. Find the maximum power that can be transmitted and the corresponding belt speed.
Power transmitted between two shafts 3.5m apart by a crossed belt drive round two pulleys 0.6m and 0.3m in diameters is 6KW. The speed of the larger pulley is 220 rpm. The permissible load on the belt is 25M per mm width of the belt which is thick. The coefficient of friction between the smaller pulley surface and the belt is 0.35 Determine:
· The necessary length of the belt
· The width of the belt
· The necessary initial tension in the belt.
A leather belt 200m x 10mm has a maximum permissible tension of 2 MN/sqm. If ratio of tension is 1.80. Determine at what velocity should it be run so as t transmit maximum power? Take density of belt material = 1100 Kg/cubic meter.
A leather belt weighing 1gm per cc. has a maximum permissible tension of 2.1 N. Determine the maximum HP that can be transmitted by a belt 250mm x 11mm in section. Take ratio of tensions = 2.
In an open belt drive, pulleys are 500mm and 1200mm in diameter on parallel shafts 4m apart. The maximum tension in the belt is limited to 1800N Take coefficient of friction 0.3. The driving pulley 1200mm dia. Is running at 210 rpm, calculate power transmitted by the belt drive.
A shaft running at 100 rpm drives another shaft at 200 rpm and transmit 11.25 KW. The belt is 100mm wide and 12mm thick and µ=0.25. the distance between the shafts is 2.5m and the diameter of the smaller pulley is 0.5m. Calculate the stress in the belt in case of
· Open belt drive
· A crossed belt drive
A shaft rotates at 200 rpm drives another shaft at 300 rpm and transmit 8 HP through a belt. The belt is 10cm wide and 1cm thick. The distance between the shaft is 4m. The smaller pulley is 50cm in diameter. Calculate the stress
· In open belt drive
· In crossed belt drive
· Take µ=0.3, Neglect centrifugal tension.
A rope drive transmits 80 KW through a 1.5m diameter 45 deg. Grooved pulley rotating at 200 rpm. Coefficient of friction between the ropes and the pulley grooves is 0.3 and angle of lap is 160 deg. The mass of each rope is 0.6 kg/m and can safely take a pull of 800N. Taking centrifugal tension into account. Determine
· Number of ropes required for the drive.
· Initial tension in the rope.
A flat belt is required to transmit 35 KW from a pulley of 1.5m effective diameter running at 300 rpm. The angle of contact is spread over 11/24 of the circumference and the coefficient of friction between the belt and the pulley is 0.3. The belt thickness is 9.5mm and its density is 1100 Kg/cubic meter. If the permissible stress is 2.5 N/mm square. Determine the width of belt required.
A simple screw jack has square threaded screw of 50mm diameter and 10mm pitch. The coefficient of friction at the screw thread is 0.16. Find the force required at the end of 600mm handle to raise a load of 2KN.
The number of teeth on the worm wheel of a single threaded worm and worm wheel is 60. Calculate the velocity ratio id the diameter of the effort wheel is 250mm and that of load drum is 125mm. The effort required to lift the load of 500N by this machine is 25N. Find the efficiency of the machine.
In a lifting machine, the efforts required to lift loads of 200N and 300N are 50N and 60N respectively. If velocity ratio of the machine is 20, Determine
· Efficiencies corresponding to 200N and 300N.
· Effort loss in friction in both cases
· Maximum efficiency of machine.
Belt Drive and Lifting machines
A belt 100mm wide and 8mm thick is transmitting power of a belt of speed of 1600m/minute. The angle of lap for the smaller pulley is 165 deg. And the coefficient of friction is 0.3. The maximum permissible stress in belt is 2MN/sq.m. and the mass of belt is 0.9 kg/m. find the power transmitted and the initial tension in the belt.
An open belt running over two pulleys 1.5m and 1.0m diameter connects two parallel shafts 4.80m apart. The initial tension in the belt when stationary is 3000N. If the smaller pulley is rotating at 600 rpm and coefficient of friction between the belt and pulley is 0.3. Determine the power transmitted taking centrifugal tension into account. The mass of the belt is given as 0.6703 kg/m length.
A belt 200mm wide and 8mm thick is transmitting power of a belt of speed of 1700m/minute. The angle of lap for the smaller pulley is 165 deg. And the coefficient of friction is 0.25. The maximum permissible stress in belt is 2500 KN/sq.m. and the mass of belt is 10 KN/cubic m. Find the maximum power that can be transmitted and the corresponding belt speed.
Power transmitted between two shafts 3.5m apart by a crossed belt drive round two pulleys 0.6m and 0.3m in diameters is 6KW. The speed of the larger pulley is 220 rpm. The permissible load on the belt is 25M per mm width of the belt which is thick. The coefficient of friction between the smaller pulley surface and the belt is 0.35 Determine:
· The necessary length of the belt
· The width of the belt
· The necessary initial tension in the belt.
A leather belt 200m x 10mm has a maximum permissible tension of 2 MN/sqm. If ratio of tension is 1.80. Determine at what velocity should it be run so as t transmit maximum power? Take density of belt material = 1100 Kg/cubic meter.
A leather belt weighing 1gm per cc. has a maximum permissible tension of 2.1 N. Determine the maximum HP that can be transmitted by a belt 250mm x 11mm in section. Take ratio of tensions = 2.
In an open belt drive, pulleys are 500mm and 1200mm in diameter on parallel shafts 4m apart. The maximum tension in the belt is limited to 1800N Take coefficient of friction 0.3. The driving pulley 1200mm dia. Is running at 210 rpm, calculate power transmitted by the belt drive.
A shaft running at 100 rpm drives another shaft at 200 rpm and transmit 11.25 KW. The belt is 100mm wide and 12mm thick and µ=0.25. the distance between the shafts is 2.5m and the diameter of the smaller pulley is 0.5m. Calculate the stress in the belt in case of
· Open belt drive
· A crossed belt drive
A shaft rotates at 200 rpm drives another shaft at 300 rpm and transmit 8 HP through a belt. The belt is 10cm wide and 1cm thick. The distance between the shaft is 4m. The smaller pulley is 50cm in diameter. Calculate the stress
· In open belt drive
· In crossed belt drive
· Take µ=0.3, Neglect centrifugal tension.
A rope drive transmits 80 KW through a 1.5m diameter 45 deg. Grooved pulley rotating at 200 rpm. Coefficient of friction between the ropes and the pulley grooves is 0.3 and angle of lap is 160 deg. The mass of each rope is 0.6 kg/m and can safely take a pull of 800N. Taking centrifugal tension into account. Determine
· Number of ropes required for the drive.
· Initial tension in the rope.
A flat belt is required to transmit 35 KW from a pulley of 1.5m effective diameter running at 300 rpm. The angle of contact is spread over 11/24 of the circumference and the coefficient of friction between the belt and the pulley is 0.3. The belt thickness is 9.5mm and its density is 1100 Kg/cubic meter. If the permissible stress is 2.5 N/mm square. Determine the width of belt required.
A simple screw jack has square threaded screw of 50mm diameter and 10mm pitch. The coefficient of friction at the screw thread is 0.16. Find the force required at the end of 600mm handle to raise a load of 2KN.
The number of teeth on the worm wheel of a single threaded worm and worm wheel is 60. Calculate the velocity ratio id the diameter of the effort wheel is 250mm and that of load drum is 125mm. The effort required to lift the load of 500N by this machine is 25N. Find the efficiency of the machine.
In a lifting machine, the efforts required to lift loads of 200N and 300N are 50N and 60N respectively. If velocity ratio of the machine is 20, Determine
· Efficiencies corresponding to 200N and 300N.
· Effort loss in friction in both cases
· Maximum efficiency of machine.
Monday, December 3, 2007
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