Quiz: Mechanical Engineering
Exam: ISRO (TECHNICAL ASST.)
Each question carries 4 mark.
Negative marking: 1 mark
Time: 15 Minute
Q1. Plastic toys are usually produced by using:
(a) Shell moulding
(b) Green sand moulding
(c) Plaster moulding
(d) Injection moulding
Q2. Austenite is a solid solution of carbon in________iron.
Q3. Boyle’s law i.e. pV = constant is applicable to gases under
(a) all ranges of pressure
(b) only small range of pressures
(c) high range of pressures
(d) steady change of pressures
Q4. In a cyclic process, the work done by the system is 20 kJ, -30 kJ, -5 kJ and 10 kJ. What is the net-heat transfer(kJ) for the cyclic process?
Q5. Stirling and Ericsson cycles are
(a) reversible cycles
(b) irreversible cycles
(c) quasi-static cycles
(d) semi-reversible cycles
Q6. The dry saturated steam at very low pressure, (5 – 10 kg/cm^2) when throttled to atmosphere will become
(c) remain dry saturated
Q7. Which of the following statement is correct for the modulus of resilience?
(a) It is the ratio of maximum stress energy and unit volume
(b) It is the ratio of maximum strain energy and unit volume
(c) It is the ratio of proof resilience and unit volume
(d) It is the ratio of proof resilience and unit area
Q8. In gears, interference takes place when______
(a) Tip of tooth of a mating gear digs into the portion between base and root circles
(b) Gears do not move smoothly in the absence of lubrication
(c) Pitch of the gear is not same
(d) Gear teeth are undercut
Q9. For a submerged curved surface, the component of force due to static liquid is equal to _______
(a) Weight of the liquid supported by curved surface
(b) Force on a projection of the curved surface on a vertical plane
(c) Area of curved surface × pressure at the centroid of the submerged area
(d) None of these
Q10. Anti-friction bearings are:
1. Sleeve bearings
2. Hydrodynamic bearings
3. Thin lubricated bearings
4. Ball and roller bearings
(a) only A
(b) only B and C
(c) only C
(d) only D
S1. Ans (d)
Sol. Injection moulding is a method to obtain molded products by injecting plastic materials melted by heat into a mould, and then cooling and solidifying them. The method is suitable for the mass production of products with complicated shapes, and takes a large part in the area of plastic processing.
S2. Ans (c)
Sol. Austenite is a solid solution of carbon in gamma iron. The solid solution of carbon in a non-magnetic form of iron is stable at high temperatures. It is a constituent of some forms of steel.
S3. Ans (b)
Sol. All gas laws are applicable for ideal gases or the gases at high temperature and low pressure.
S4. Ans (a)
Sol. We know that
First law of thermodynamics ∮dQ=∮dW
So, net heat transfer = 20-30-5+10 = -5 kJ
S5. Ans (a)
Sol. Stirling and Ericsson cycles both are reversible cycles. Stirling cycle has constant volume heat addition and rejection and Ericsson cycle has constant pressure heat addition and rejection.
S6. Ans (a)
Sol. The dry saturated steam at very low pressure, (5 – 10 kg/cm^2) when throttled to atmosphere will become wet.
S7. Ans (c)
Sol. The modulus of resilience is the maximum amount of energy per volume that a material can absorb while elastically deforming.
S8. Ans (a)
Sol. In gears, interference takes place when tip of tooth of a mating gear digs into the portion between base and root circles.
S9. Ans (a)
Sol. For a submerged curved surface, the component of force due to static liquid is equal to weight of the liquid supported by curved surface up to the free surface of liquid.
S10. Ans (d)
Sol. An anti-friction bearing, also known as a rolling contact bearing, is justified over a journal or fluid film bearing when very little friction is needed for low differential. E.g. Ball and roller bearing etc.