May, 2022Flame Institute

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57. A wire of length L and radius r is rigidly fixed at one end. On stretching the other end of the wire with a force F, the increase in its length is l. If another wire of same material but of length 2L and radius 2r is stretched with a force of 2F, the increase in its length will be

(a) l (b) 2l (c) l /2 (d) l /4 Answer-a (12)

56. Liquids have no Poisson’s ratio, because

(a) It has no definite shape (b) It has greater volume (c) It has lesser density than solid (d) None of the above Answer-a (3)

The angular velocity of rotation of star (of mass M and radius R) at which the matter start to escape from its equator will be

Answer: c (1)

55. If Young’s modulus for a material is zero, then the state of material should be

(a) Solid (b) Solid but powder (c) Gas (d) None of the above …

54. The elastic limit for a gas

(a) Exists (b) Exists only at absolute zero (c) Exists for a perfect gas (d) Does not exist Answer-a (19)

52. If the density of the material increases, the value of Young’s modulus

(a) Increases (b) Decreases (c) First increases then decreases (d) First decreases then increases Answer-a (18)

51. The longitudinal strain is only possible in

(a) Gases (b) Fluids (c) Solids (d) Liquids Answer-c (11)

49.The quality of the material which opposes the change in shape, volume or length is called

(a) Intermolecular repulsion (b) Intermolecular behaviour (c) Viscosity (d) Elasticity Answer-d (8)

Given mass of the moon is 1/81 of the mass of the earth and corresponding radius is 1/4 of the earth. If escape velocity on the earth surface is 11.2 km/s, the value of same on the surface of the moon is

(a) 0.14 km/s (b) 0.5 km/s (c) 2.5 km/s (d) 5 km/s Answer: c (4)

47. When compared with solids and liquids, the gases have

(a) Minimum volume elasticity (b) Maximum volume elasticity (c) Maximum Young’s modulus (d) Maximum modulus of rigidity Answer-a (13)

The escape velocity of a body on the surface of the earth is 11.2 km/s. If the earth’s mass increases to twice its present value and the radius of the earth becomes half, the escape velocity would become

(a) 5.6 km/s (b) 11.2 km/s (remain unchanged) (c) 22.4 km/s (d) 44.8 km/s Answer: c (5)

The escape velocity on earth is 11.2 km/s. On another planet having twice radius and 8 times mass of the earth, the escape velocity will be

(a) 3.7 km/s (b) 11.2 km/s (c) 22.4 km/s (d) 43.2 km/s Answer: c (5)

45. In suspended type moving coil galvanometer, quartz suspension is used because

(a) It is good conductor of electricity (b) Elastic after effects are negligible (c) Young’s modulus is greater (d) There is no elastic limit Answer-b (12)

The s – block element used as a catalyst in the manufacture of Buna – S rubber is

a. Mg b. Ca c. Ba d. Na Ans. c (3)

145. A disc of mass M and radius R rolls in a horizontal surface and then rolls up an inclined plane as shown in the fig. If the velocity of the disc is v, the height to which the disc will rise will be

(a) 3v2/ 2g (b) 3v2/4g (c) v2/4g (d) v2/2g Ans. b (55)

37.The ratio of diameters of two wires of same material is n : 1. The length of wires are 4 m each. On applying the same load, the increase in length of thin wire will be

(a) n2 times (b) n times (c) 2n times (d) None of the above Answer-a (10)

Which of the following polymer is used in pigment

a. Buna – S b. Neoprene c.Teflon d. Orlon Ans. a (11)

41. Two identical wires of rubber and iron are stretched by the same weight, then the number of atoms in the iron wire will be

(a) Equal to that of rubber (b) Less than that of the rubber (c) More than that of the rubber (d) None of the above Answer-c (7)

Biodegradable polymer which can be

a. PHBV b. Buna- N c. Nylon 6, 6 d. Nylon 2- nylon 6 Ans. d (6)

146.Two uniform similar discs roll down two inclined planes of length S and 2S respectively as shown is the fig. The velocities of two discs at the points A and B of the inclined planes are related as

(a) v1 = v2 (b) v1 =2v2 (c) v1 = v1 (v2/4) (d) v1 =( 3/4) v2 Ans. a (59)

which of the following is a biodegradable polymer

a. Cellulose b. Polythene c. Polyvinyl chloride d. Nylon -6 Ans. a (12)

The escape velocity for the earth is 11.2 km/sec. The mass of another planet is 100 times that of the earth and its radius is 4 times that of the earth. The escape velocity for this planet will be

(a) 112.0 km/s (b) 5.6 km/ (c) 280.0 km/s (d) 56.0 km/s Answer: d (8)

36. If a load of 9 kg is suspended on a wire, the increase in length is 4.5 mm. The force constant of the wire is

(a) 0.49×104 N/m (b) 1.96×104 N/m (c) 4.9×104 N/m (d) 0.196×104 N/m Answer-b (16)

The escape velocity of an object on a planet whose g value is 9 times on earth and whose radius is 4 times that of earth in km/s is

(a) 67.2 (b) 33.6 (c) 16.8 …

44. After effects of elasticity are maximum for

(a) Glass (b) Quartz (c) Rubber (d) Metal Answer-a (17)

43. The elasticity of invar

(a) Increases with temperature rise (b) Decreases with temperature rise (c) Does not depend on temperature (d) None of the above Answer-c (46)

42. The force constant of a wire does not depend on

(a) Nature of the material (b) Radius of the wire (c) Length of the wire (d) None of the above Answer-d (7)

37. The escape velocity of a planet having mass 6 times and radius 2 times as that of earth is

(a) √3 ve (b) 3 ve (c) √2 ve (d) 2 ve Answer: a (6)

39. A steel wire is stretched with a definite load. If the Young’s modulus of the wire is Y. For decreasing the value of Y

(a) Radius is to be decreased (b) Radius is to be increased (c) Length is to be increased (d) None of the above ANSWER-D (11)

‘Celanese silk’ is

a. Cellulose trinitrate b. Cellulose acetate c. Cellophane d. Pyroxylin Ans. b (6)

Which of the following is currently used as a tyre cord

a. Terylene b. Polyethylene c. Polypropylene d. Nylon- 6 Ans. d (11)

35. A weight of 200 kg is suspended by vertical wire of length 600.5 cm. The area of cross-section of wire is 1mm2. When the load is removed, the wire contracts by 0.5 cm. The Young’s modulus of the material of wire will be

(a) 2.35×1012 N/m2 (b) 1.35×1010 N/m2 (c) 13.5×1011 N/m2 (d) 23.5×109 N/m2 Answer- (8)

The polymer used for making contact lenses for eyes is

a. Polymethylmethacrylate b. Polyethylene c. Polyethylacrylate d. Nylon – 6 Ans. a (5)

144. A ring of radius 4a is rigidly fixed in vertical position on a table. A small disc of mass m and radius a is released as shown in the fig. When the disc rolls down, without slipping, to the lowest point of the ring, then its speed will be

(a) √ga (b) √2ga (c) √3ga (d) √4ga Ans. d (129)

Plexiglass is a commercial name of

a. Glyptal b. Polyacrylo nitrile c. Polythylacrylate d. Polyethyl acrylate Ans. a (43)

34. Two wires of copper having the length in the ratio 4 : 1 and their radii ratio as 1 : 4 are stretched by the same force. The ratio of longitudinal strain in the two will be

(a) 1 : 16 (b) 16 : 1 (c) 1 : 64 (d) 64 : 1 Answer-b (2)

Which of the following has been used in the manufacture of non- inflammable photographic films

a. Cellulose nitrate b. Cellulose acetate c. Cellulose xanthate d. Cellulose perchlorate Ans. b (5)

The escape velocity from the surface of earth is Ve . The escape velocity from the surface of a planet whose mass and radius are 3 times those of the earth will be

(a) Ve (b) 3 Ve (c) 9 Ve (d) 27 Ve Answer: a (4)

Which of the following statements about low density polythene is FALSE

a. It is poor conductor of electricity b. Its synthesis required dioxygen or a peroxide initiator as a catalyst c. It is used in the manufacture of buckets, dust-bins etc d. Its synthesis requires high pressure Ans. b (6)

Polymer used in bullet proof glass is

a. Lexan b. PMMA c. Nomex d. Kevlar Ans. a (7)

Month: May 2022

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