UPPSC Lec'21 ME: Daily Practices Quiz. 01-Oct-2021

Quiz: Mechanical Engineering
Exam: UPPSC Lecturer
Topic: Miscellaneous

Each question carries 1 mark
Negative marking: 1/4 mark
Time: 6 Minutes

Q1. A pitot static tube is used to measure
(a) Stagnation pressure
(b) Static pressure
(c) Dynamic pressure
(d) Difference between the static pressure and dynamic pressure

Q2. The constant pressure lines ……. on a Mollier diagram
(a) Are equispaced throughout
(b) First Converge and then diverge
(c) Diverge from left to right
(d) Diverge from right to left

Q3. Splines are used when
(a) Power to be transmitted is low
(b) High rotational speeds are involved
(c) High torque is to be transmitted
(d) There is need for axial relative motion between the shaft and hub

Q4. The state of stress at a point in a loaded member is σ_x=400 MPa, σ_y=-400 MPa and σ_xy=300 MPa. The principal stresses 1 and 2 are
(a) 300 MPa and –700 MPa
(b) 400 MPa and –600 MPa
(c) 500 MPa and – 500 MPa
(d) 600 MPa and – 400 MPa

Q5. Diagram factor is defined as the ratio of
(a) Actual indicated work to hypothetical indicated work
(b) Hypothetical indicated work to actual indicated work
(c) Actual work to isentropic work
(d) Hypothetical work to Actual Work

Q6. The type of valve which is used in reciprocating refrigerant compressors?
(a) Mushroom valve
(b) Puppet valve
(c) Plate valve
(d) Throttle valve

Solutions

S1. Ans. (c)
Sol. A simple pitot tube measure stagnation pressure but a pitot static tube is used to measure dynamic pressure.

S2. Ans. (c)
Sol. Constant pressure lines diverge from left to right on Mollier diagram.
Mollier diagram is drawn between enthalpy (h) on y-axis and entropy (s) on x-axis.
The slope of the constant pressure line on h-s curve is absolute temperature.

S3. Ans. (d)
Sol. Splines are used to provide torque and speed from the shaft to the hub or vice-versa.

S4. Ans.(c)
Sol.
Principal stress,
σ_1,σ¬_2=(400 – 400)/2 ± √(((400 + 400)/2)^2+300²)
= ±√(400^2+300²) = ± 500 MPa

S5. Ans. (a)
Sol. Diagram factor=(Area of actual indicator diagram)/(Area of hypothetical indicator diagram)

S6. Ans. (c)
Sol. Plate valve is used in the reciprocating refrigerant compressor.