**The concept of stream function which is based on the principle of continuity is applicable to**

Options are :

- Irrotational flow only
- Three-dimensional flow
- Uniform flow
- Two-dimensional flow

**Answer : **Two-dimensional flow

Heat Transfer Practice Questions (Mechanical Engineering) Set 1

**A stream line is one**

Options are :

- In which the flow cannot cross the bounding surface
- Which has a constant area throughout its length so that the velocity remains constant
- In which stream function does not change
- None of these

**Answer : **In which the flow cannot cross the bounding surface

**Equilibrium
is called …………… if a body does not return to its original position from
the slightly displaced angular position and heels farther away, when
given a small angular displacement**

Options are :

- Any of these
- Stable
- Unstable
- Neutral

**Answer : **Unstable

**What is the reciprocal of compressibility?**

Options are :

- Bulk modulus of elasticity
- Any of the above
- Young’s modulus of elasticity
- Shear modulus of elasticity

**Answer : **Bulk modulus of elasticity

Engineering Mechanics Practice Questions (Mechanical) Set 1

**Bernoulli’s equation of the form (p/w + v2/2g + z = constant) represents total energy per unit**

Options are :

- Specific weight
- Mass
- Volume
- Weight

**Answer : **Weight

**The momentum convection factor ? is used to account for**

Options are :

- Non-uniform distribution of velocities at inlet and outlet sections
- Change in total energy
- Change in direction of flow
- Change in mass rate of flow

**Answer : **Non-uniform distribution of velocities at inlet and outlet sections

**The point of application of the force of buoyancy on the body is known as**

Options are :

- Centre of gravity
- Centre of buoyancy
- Metacentre
- None of these

**Answer : **Centre of buoyancy

**A pitot-tube is used to measure**

Options are :

- Pressure of flow
- Flow rate
- Velocity of flow
- Total energy

**Answer : **Velocity of flow

**Fluids which do not follow the linear relationship between shear stress and rate of deformation are termed as**

Options are :

- Ideal fluids
- Newtonian fluids
- Non-Newtonian fluids
- None of these

**Answer : **Non-Newtonian fluids

**A floating body is in stable equilibrium when**

Options are :

- The metacentre is below its centre of gravity
- The metacentre is above its centre of gravity
- The metacentric height is zero
- Its centre of gravity is below the centre of buoyancy

**Answer : **The metacentre is above its centre of gravity

**The drag and lift forces experienced by an object placed in a fluid stream are due to**

Options are :

- Pressure and gravity
- Pressure and viscosity
- Viscosity and turbulence
- Pressure and turbulence

**Answer : **Pressure and viscosity

**The stagnation pressure (Ps) and temperature (Ts) are**

Options are :

- More than their ambient counterparts
- The same as in ambient flow
- None of these
- Less than their ambient counterparts

**Answer : **More than their ambient counterparts

**The critical depth is the depth of flow at which**

Options are :

- The unit discharge is minimum
- The specific energy is minimum
- The specific energy is maximum
- The Froude number is less than unity

**Answer : **The specific energy is minimum

**How can the separation of boundary prevented?**

Options are :

- All of these
- Providing the bypass in the slotted wing
- Suction of the slow moving fluid by a suction slot
- Providing small divergence in a diffuser

**Answer : **All of these

**Loss of head at exit of a pipe is given as**

Options are :

- V^(3) /2g
- V/2g
- None of these
- V^(2) /2g

**Answer : **V^(2) /2g

**Prandtl is regarded as the father of modern fluid mechanics on account of**

Options are :

- His fundamental research in the field of aircraft engineering
- His new interpretations on fluid resistance
- None of these
- His pioneering research on flow of low viscosity fluids bringing forward a new concept of boundary layer

**Answer : **His pioneering research on flow of low viscosity fluids bringing forward a new concept of boundary layer

**The pressure drag depends upon**

Options are :

- The boundary layer formation
- The shear stresses generated on the body surface
- The separation of boundary layer and the size of the wake
- The characteristics of the oncoming flow

**Answer : **The separation of boundary layer and the size of the wake

**…………………….determine the friction factor for turbulent flow in a rough pipe**

Options are :

- Mach number and relative roughness
- Reynolds number and relative roughness
- Froude number and Mach number
- Froude number and relative roughness

**Answer : **Reynolds number and relative roughness

**Due to ………… phenomena water hammer is caused**

Options are :

- Incompressibility of fluid
- Sudden opening of a valve in a pipeline
- The material of pipe being elastic
- Sudden closure of a valve in pipe flow

**Answer : **Sudden closure of a valve in pipe flow

**At what value of head lost due to friction in pipe, will the power transmitted through the pipe be maximum?**

Options are :

- 1/8th of the total supply head
- 1/4th of the total supply head
- 1/2 of the total supply head
- 1/3rd of the total supply head

**Answer : **1/4th of the total supply head

**Aging of pipes implies**

Options are :

- None of these
- Increase in absolute roughness linearly with time and hence friction factor
- A decrease in the value of friction factor
- Pipe becoming smoother with time

**Answer : **Increase in absolute roughness linearly with time and hence friction factor

**When does a hydraulic jump occur in a channel?**

Options are :

- The bed slope is adverse
- Flow changes from sub critical to supercritical
- The bed slope changes from steep to mild
- None of these

**Answer : **The bed slope changes from steep to mild

**The friction drag is primarily due to**

Options are :

- Shear stresses generated due to viscous action
- Separation of boundary layer
- None of these
- Weight component in the direction of flow

**Answer : **Shear stresses generated due to viscous action

**The sonic speed in an ideal gas varies**

Options are :

- None of these
- Directly as the absolute pressure
- Inversely as the absolute temperature
- Inversely as bulk modulus

**Answer : **None of these

**The sonic velocity in a fluid medium is directly proportional to**

Options are :

- Mach number
- Square root of temperature
- None of these
- Pressure

**Answer : **Square root of temperature

**Which of the following conditions / requirements is necessary to induce lift on an object?**

Options are :

- The object should be so shaped that there are zones of high and low velocities resulting in pressure difference between upper side and bottom side of the object
- None of these
- The shape of the object should be so designed that the pressure distribution over its surface is symmetrical
- The object should be symmetrical and the axis of the symmetry be aligned parallel to the flow direction

**Answer : **The object should be so shaped that there are zones of high and low velocities resulting in pressure difference between upper side and bottom side of the object

**The Darcy-Weisbach friction factor ‘f’ which is a direct measure of resistance to flow in pipes depends on**

Options are :

- Relative roughness, velocity and viscosity
- Roughness height, diameter and velocity
- Roughness height, diameter, velocity and kinematic viscosity
- Relative roughness, diameter and viscosity

**Answer : **Roughness height, diameter, velocity and kinematic viscosity

**When a turbulent flow is considered steady?**

Options are :

- The discharge remains constant
- Temporal mean velocity at a point remains constant with time
- The velocity at a point does not change with time
- The algebraic sum of velocity fluctuation is zero

**Answer : **Temporal mean velocity at a point remains constant with time

**The pressure gradient in the direction of flow is equal to the shear gradient in the direction**

Options are :

- Parallel to the direction of flow
- Normal to the direction of flow
- None of the above
- Either of the above

**Answer : **Normal to the direction of flow

**In dimensional analysis the Buckingham’s ?-theorem is widely used and expresses the resulting equation in terms of**

Options are :

- The repeating variables
- (n-m) dimensionless parameters
- n dimensionless parameters
- Geometric, kinematic, and dynamic variables

**Answer : **(n-m) dimensionless parameters

**In
turbulent flow the velocity distribution is a function of the distance y
measured from the boundary surface and shear friction velocity Up and
follows a**

Options are :

- Hyperbolic law
- Logarithmic law
- Parabolic law
- Linear law

**Answer : **Logarithmic law

**Dimensional analysis is used to**

Options are :

- Derive rational formulae for a flow phenomenon
- All of these
- Derive equations expressed in terms of non-dimensional parameters to show the relative significance of each parameter
- Test the dimensional homogeneity of any equation of fluid motion

**Answer : **All of these

**How much time is required to empty a tank through an orifice at its bottom?**

Options are :

- 2A?H1/Cd.a^(2.2g)
- 2A?H1/Cd.a.?2g
- 4A?H1/Cd.a.?2g
- A?H1/Cd.a.?2g

**Answer : **2A?H1/Cd.a.?2g

**What is the most essential feature of a turbulent flow?**

Options are :

- Velocity at a point remains constant with time
- Velocity and pressure at a point exhibit irregular fluctuations of high frequency
- Large discharge
- High velocity

**Answer : **Velocity and pressure at a point exhibit irregular fluctuations of high frequency

**An error of 1% measuring H will produce …………..error in discharge over a rectangular notch or weir**

Options are :

- 2%
- 1%
- 1.5%
- 2.5%

**Answer : **1.5%

**To
apply Buckingham’s ?-theorem, ‘m’ repeating variables amongst the ‘n’
variables influencing the phenomenon are selected such that they**

Options are :

- Must always contain the dependent variables
- Belong to kinematic and dynamic category of variables
- None of these
- In combination contain each of the m fundamental dimensions involved in the problem

**Answer : **In combination contain each of the m fundamental dimensions involved in the problem

**Intensity of turbulence is**

Options are :

- None of these
- The mean time interval between the reversals in the sign of velocity fluctuation
- The average K.E. of turbulence
- The violence of turbulent fluctuations and is measured by the root mean square value of velocity fluctuations

**Answer : **The violence of turbulent fluctuations and is measured by the root mean square value of velocity fluctuations

**Loss of head due to sudden enlargement is given as**

Options are :

- (V1^(2) - V2^(2))/2g
- (V1 - V2)^(2)/2g
- (V1^(3) - V2^(3))/2g
- (V1 - V2)^(3)/2g

**Answer : **(V1 - V2)^(2)/2g