Question 1

What is Mach number?&#10;A)speed of object * speed of sound&#10;B)speed of object /speed of sound&#10;C)speed of object + speed of sound&#10;D)speed of object- speed of sound

Accepted Answer

Mach number is defined as the ratio of the speed of an object to the speed of sound in the surrounding medium.

Question 2

Which of the following kinetic friction is smaller?&#10;A)limiting friction&#10;B)static friction&#10;C)rolling friction&#10;D)sliding friction

Accepted Answer

Rolling friction is generally smaller than limiting friction, static friction, and sliding friction because it involves the rolling of an object over a surface, which typically encounters less resistance than sliding or starting to move an object from rest.

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

0.27

Accepted Answer

The coefficient of static friction ($\mu_s$) can be calculated using the formula $\mu_s = \tan(\theta)$, where $\theta$ is the angle of inclination at which the object just begins to slide. For $\theta = 15°$, $\mu_s = \tan(15°) \approx 0.27$.

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.&#10;A)60kg f&#10;B)48kg f&#10;C)25kg f&#10;D)32kg f

Accepted Answer

The force of friction can be calculated using the formula $F = \mu \times N$, where $F$ is the force of friction, $\mu$ is the coefficient of friction, and $N$ is the normal force. In this case, the normal force is equal to the weight of the scooter, which is 120kg f. Therefore, $F = 0.4 \times 120kg f = 48kg f$.

Question 5

How is friction due to air reduced?&#10;A)streamlining&#10;B)lubrication&#10;C)by using ball bearings&#10;D)by polishing

Accepted Answer

Streamlining reduces friction due to air by shaping objects so that air flows more smoothly around them, thereby reducing drag.

Question 6

Friction can be increased by______________&#160;&#160;&#160;&#160;&#10;A)using air cushion&#10;B)lubricants&#10;C)using sand&#10;D)using ball bearings

Accepted Answer

Friction can be increased by adding materials that create more resistance between surfaces, such as sand. Sand particles increase the roughness of surfaces, leading to higher friction.

Question 7

When moving along a curved path, he&#10;A)leans inwards&#10;B)leans outwards&#10;C)is still&#10;D)leans sideways

Accepted Answer

When moving along a curved path, a person leans inwards due to the centripetal force required to keep them moving in a circular path. This inward force is what causes the person to lean towards the center of the curve.

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.&#10;A)0.20m&#10;B)0.0454m&#10;C)0.45m&#10;D)0.020m

Accepted Answer

The correct answer is found using the formula for the elevation of the outer rail ($h$) in railway tracks, which is given by $h = \frac{v^2}{gR}$, where $v$ is the speed of the train in m/s, $g$ is the acceleration due to gravity (approximately $9.8 m/s^2$), and $R$ is the radius of the curve in meters. First, convert the speed from km/h to m/s: $48 \times \frac{1000}{3600} = 13.33 m/s$. Then, plug the values into the formula: $h = \frac{(13.33)^2}{9.8 \times 400} = 0.0454m$.

Question 9

When a gas is pushed through a pipe, the gaseous molecules are by the pipe's walls&#10;A)attracted&#10;B)absorbed&#10;C)deflected&#10;D)dissipated

Accepted Answer

When a gas is pushed through a pipe, the gaseous molecules collide with the pipe's walls and are deflected. This means they are bounced off in different directions, which is a fundamental behavior of gases in confined spaces.

Question 10

In fluid dynamics, the velocity of the fluid in the stagnation point is&#10;A)zero&#10;B)infinite&#10;C)non-existent&#10;D)negative

Accepted Answer

At the stagnation point in fluid dynamics, the velocity of the fluid is zero because this is the point where the fluid comes to a complete stop.

Question 11

If the speed of sound is much____________than that of the gas, the gas density will stay constant.&#10;A)smaller&#10;B)larger&#10;C)equal to&#10;D)non-existent

Accepted Answer

The answer of If the speed of sound is much____________than...

Question 12

Isentropic nozzle flow states about the movement of a gas or fluid through a narrow orifice without an increase or decrease in&#10;A)accelerating&#10;B)decelerating&#10;C)equilibrium&#10;D)exponential increase

Accepted Answer

The answer of Isentropic nozzle flow states about the movement...

Question 13

To refrain from separation in subsonic nozzles, the expansion angle must not be more than______________&#10;A)10 degrees&#10;B)20 degrees&#10;C)30 degrees&#10;D)40 degrees

Accepted Answer

The answer of To refrain from separation in subsonic nozzles,...

Question 14

Gas flows through the nozzle from an area of pressure (called the chamber) to one of pressure&#10;A)high, low&#10;B)low, high&#10;C)same, same&#10;D)constant, infinite

Accepted Answer

The answer of Gas flows through the nozzle from an...

Question 15

Converging-diverging nozzle is also known as______________&#160;&#160;&#10;A)pascal nozzle&#10;B)bernouille's nozzle&#10;C)toricelli's nozzle&#10;D)de laval' nozzle

Accepted Answer

The answer of Converging-diverging nozzle is also known as______________&#160;&#160;&#10;A)pascal nozzle&#10;B)bernouille's...

Question 16

When the pressure chamber is big, the flow velocities are______________&#10;A)large&#10;B)negligible&#10;C)constant&#10;D)increasing

Accepted Answer

The answer of When the pressure chamber is big, the...

Question 17

For a compressible, ideal gas, mass flow rate depends on parameters such as flow area, pressure, temperature, properties of the gas, and______________&#10;A)avogardo's number&#10;B)mach number&#10;C)reynold's number&#10;D)le-grange' number

Accepted Answer

The answer of For a compressible, ideal gas, mass flow...

Question 18

Which type of boilers use orifice to control the flow circulation?&#10;A)natural circulation boilers&#10;B)forced convection boilers&#10;C)once-through boilers&#10;D)positive forced circulation boilers

Accepted Answer

The answer of Which type of boilers use orifice to...

Question 19

What is the advantage of having smaller ratio of water to steam space?&#10;A)steam can be generated at a faster even if the boiler is cold&#10;B)increases the rate of evaporation&#10;C)water is made cyclic, i.e., from boiler drum to water tube and back to drum&#10;D)helps in mobilizing the boiler

Accepted Answer

The answer of What is the advantage of having smaller...

Question 20

Which are the major types of boilers that are operated in world today?&#10;A)natural circulation boiler&#10;B)forced circulation boiler&#10;C)fire tube boiler&#10;D)once through boiler

Accepted Answer

The answer of Which are the major types of boilers...

Question 21

How many level indicators are there in the water level indicator of a boiler?&#10;A)1&#10;B)2&#10;C)3&#10;D)4

Accepted Answer

The answer of How many level indicators are there in...

Question 22

What is the function of pressure gauge in the boiler?&#10;A)to indicate steam pressure&#10;B)to indicate water pressure&#10;C)to indicate air pressure&#10;D)to indicate flue gas pressure

Accepted Answer

The answer of What is the function of pressure gauge...

Question 23

other than Steam stop valve in the boiler which is the other similar type of valve used?&#10;A)non-reversible valve&#10;B)transient valve&#10;C)reversible valve&#10;D)junction valve

Accepted Answer

The answer of other than Steam stop valve in the...

Question 24

What is the function of Blow down valve of a boiler?&#10;A)to remove sludge&#10;B)to build sediments&#10;C)to remove flue gas&#10;D)to remove ash

Accepted Answer

The answer of What is the function of Blow down...

Question 25

What is the function of fusible plug in the boiler?&#10;A)protect the fire tube&#10;B)to trip on overload&#10;C)to act as a junction switch&#10;D)to maintain pressure

Accepted Answer

The answer of What is the function of fusible plug...

Deck 2: Friction, Mach Number, and Boiler Operations