Deck 2: Friction, Mach Number, and Boiler Operations

Question 1

What is Mach number?

A)speed of object * speed of sound
B)speed of object /speed of sound
C)speed of object + speed of sound
D)speed of object- speed of sound

Answer 1

speed of object /speed of sound

Question 2

Which of the following kinetic friction is smaller?

A)limiting friction
B)static friction
C)rolling friction
D)sliding friction

Answer 2

rolling friction

Question 3

A mass of 4kg rests on a horizontal plane. The plane is gradually inclined until at an angle ?= 15° with the horizontal, the mass just begins to slide. What is the coefficient of static friction between the block and the surface?

A)0.814
B)0.27
C)1.5
D)3.5

Answer 3

0.27

Question 4

A scooter weighs 120kg f. Brakes are applied so that wheels stop rolling and start skidding. Find the force of friction if the coefficient of friction is 0.4.

A)60kg f
B)48kg f
C)25kg f
D)32kg f

Question 5

How is friction due to air reduced?

A)streamlining
B)lubrication
C)by using ball bearings
D)by polishing

Question 6

Friction can be increased by______________    

A)using air cushion
B)lubricants
C)using sand
D)using ball bearings

Question 7

When moving along a curved path, he

A)leans inwards
B)leans outwards
C)is still
D)leans sideways

Question 8

A train has to negotiate a curve of radius 400m. By how much should the putter rail be raised with respect to inner rail for speed of 48 km/h? The distance between the rails is 1m.

A)0.20m
B)0.0454m
C)0.45m
D)0.020m

Question 9

When a gas is pushed through a pipe, the gaseous molecules are by the pipe's walls

A)attracted
B)absorbed
C)deflected
D)dissipated

Question 10

In fluid dynamics, the velocity of the fluid in the stagnation point is

A)zero
B)infinite
C)non-existent
D)negative

Question 11

If the speed of sound is much____________than that of the gas, the gas density will stay constant.

A)smaller
B)larger
C)equal to
D)non-existent

Question 12

Isentropic nozzle flow states about the movement of a gas or fluid through a narrow orifice without an increase or decrease in

A)accelerating
B)decelerating
C)equilibrium
D)exponential increase

Question 13

To refrain from separation in subsonic nozzles, the expansion angle must not be more than______________

A)10 degrees
B)20 degrees
C)30 degrees
D)40 degrees

Question 14

Gas flows through the nozzle from an area of pressure (called the chamber) to one of pressure

A)high, low
B)low, high
C)same, same
D)constant, infinite

Question 15

Converging-diverging nozzle is also known as______________  

A)pascal nozzle
B)bernouille's nozzle
C)toricelli's nozzle
D)de laval' nozzle

Question 16

When the pressure chamber is big, the flow velocities are______________

A)large
B)negligible
C)constant
D)increasing

Question 17

For a compressible, ideal gas, mass flow rate depends on parameters such as flow area, pressure, temperature, properties of the gas, and______________

A)avogardo's number
B)mach number
C)reynold's number
D)le-grange' number

Question 18

Which type of boilers use orifice to control the flow circulation?

A)natural circulation boilers
B)forced convection boilers
C)once-through boilers
D)positive forced circulation boilers

Question 19

What is the advantage of having smaller ratio of water to steam space?

A)steam can be generated at a faster even if the boiler is cold
B)increases the rate of evaporation
C)water is made cyclic, i.e., from boiler drum to water tube and back to drum
D)helps in mobilizing the boiler

Question 20

Which are the major types of boilers that are operated in world today?

A)natural circulation boiler
B)forced circulation boiler
C)fire tube boiler
D)once through boiler

Question 21

How many level indicators are there in the water level indicator of a boiler?

A)1
B)2
C)3
D)4

Question 22

What is the function of pressure gauge in the boiler?

A)to indicate steam pressure
B)to indicate water pressure
C)to indicate air pressure
D)to indicate flue gas pressure

Question 23

other than Steam stop valve in the boiler which is the other similar type of valve used?

A)non-reversible valve
B)transient valve
C)reversible valve
D)junction valve

Question 24

What is the function of Blow down valve of a boiler?

A)to remove sludge
B)to build sediments
C)to remove flue gas
D)to remove ash

Question 25

What is the function of fusible plug in the boiler?

A)protect the fire tube
B)to trip on overload
C)to act as a junction switch
D)to maintain pressure