Quiz: Mechanical Engineering
Each question carries 1 mark
Negative marking: 1/4 mark
Time: 10 Minutes
Q1. Reversible adiabatic process is also called
(a) Isothermal process
(b) Isochoric process
(c) Isentropic process
(d) none of these
Q2. Hart mechanism has
(a) eight links
(b) six links
(c) four links
(d) twelve links
Q3. A rotating shaft carrying a unidirectional transverse load is subjected to:
(a) Variable bending stress
(b) Variable shear stress
(c) Constant bending stress
(d) Constant shear stress
Q4. Photochemical smog is mainly due to
(a) 〖NO〗_X and HC
(b) CO and 〖CO〗_2
(c) Excess O_2
(d) Soot and PM
Q5. When a boat enters river from a sea, one can expect
(a) to rise a little
(b) to fall a little
(c) to remain at same level
(d) depends upon boat density
Q6. In order that no shock wave develops when flow is taking place through a converging-diverging tube, Mach number at exit should be
(a) equal to 1
(b) greater than 1
(c) less than 1
(d) none of these
Q7. Which of the following is the correct method for the conversion of spring-controlled governor from unstable to stable?
(a) Increasing the ball weight
(b) Decreasing the spring stiffness
(c) Decreasing the ball weight
(d) Increasing the spring stiffness
Q8. Which one of the following assumptions in the theory of pure torsion is false?
(a) The angle of twist is uniform along the length
(b) The shaft is of uniform circular section throughout
(c) Cross-section plane before torsion remains plane after torsion
(d) All radii get twisted due to torsion
Q9. Filling or decking in a cooling tower increases the rate of heat transfer by providing
(a) increased flow of water
(b) increased flow of air
(c) increased flow of water and air
(d) a large amount of wetted surface
Q10. Two-stroke engines are used more frequently in two wheelers due to which of the following reasons?
(a) exhaust is less
(b) higher thermal efficiency
(c) higher power to weight ratio
(d) less friction
S1. Ans (c)
Sol. A Reversible Adiabatic Process is also known as Isentropic Process. It is an idealized thermodynamic process which is adiabatic and in which the work transfers of the system are frictionless; there is no transfer of heat or of matter and the process is reversible.
Sol. Some fibre is subjected to tensile and compressive bending tress.
S4. Ans (a)
Sol. Photochemical smog is produced when pollutants from the combustion of fossil fuels react with sunlight. The energy in the sunlight converts the pollutants into other toxic chemicals. In order for photochemical smog to form, there must be other pollutants in the air, specifically nitrous oxides and other volatile organic compounds (VOCs).
S5. Ans (b)
Sol. Due to density of sea water is more than that of river water, hence more volume of boat has to be sunk in the river water than that in sea water.so floor level will fall of boat in river water.
Sol. Mach number at exit should be greater than 1 for no shock wave generation when flow is taking place through a converging-diverging tube.
Sol. A spring-controlled governor is said to be stable if the radius of the balls increases with increase in the speed of the governor and vice versa. A spring-controlled governor can be made stable by decreasing the spring stiffness.
Sol. Following assumptions are made in the theory of pure torsion:
1. The material of shaft is uniform throughout
2. The shaft is of uniform circular cross-section throughout its length
3. Cross section remains plane before and after torsion.
4. All radii get twisted due to torsion
Sol. Filling or decking in a cooling tower increases the rate of heat transfer by providing increased wetted area.
Sol. Two-stroke engines are used more frequently in two wheelers due to higher power to weight ratio of these engines.