Page 1 :
WEEKL Y TEST IX, MARKS: 360M, Chemistry +Physics, , In solids, inter-atomic forces are, , {a) Totally repulsive (6) Totally attractive, , {c) Combination of (a) and (b) (d)None of these, , The potential energy U between two molecules as a function of the distance Y between them has heen, shown in the figure. The two molecules are, , {a) Attracted when x lies between 4 and B and are repelled when X lies between 8 and C, , (b) Attracted when x lies between 8 and C and are repelled when lies between A and B, , {c) Attracted when they reach B, , {d) Repelled when they reach B, , ‘The nature of molecular forces resembles with the nature of the, {a) Gravitational force (b) Nuclear force (c) Electromagnetic force (d)Weak force, , The ratio of radius of two wire of same material is 2. 1 Stretched by same force, then the ratio of, stress is, , , , {a)2.1 {b) 1.2 (ey 14 4s, Tf equal and opposite forces applied to a body tend to elongate it, the stress so produced ts called, {a) Tensile stress {b) Compressive stress (c) Tangential stress (d) Working stress, , A vertical hanging bar of length / and mass m per unit length carries a load of mass M at the lower end,, its upper end is clamped to a rigid support. The tensile force at a distance x from support is, , {a) Mg + mg(!-x) (b) Mg (c) Mg > mal (d) «ae +mig =, One end of a uniform rod of mass m) and cross-sectional area A is hung from a ceiling. The other end, of the bar 1s supporting mass mm. The stress at the midpoint 1s, , ay Alert ot 2a), fa) 7, , {b) Slow, +r), 24, , Baty +e), (©) 24, , {d) gle +6), A, , A uniform bar of square cross-section is lying along a frictionless horizontal surface. A horizontal, force ts applied to pull it from one of its ends then, , {a) The bar is under same stress throughout tls length, , (b) The bar is not under any stress because force has been applied only at one end, , {c) The bar simply moves without any stress in it, , {d) The stress developed reduces to zero at the end of the bar where no force is applied, Which one of the following quantities does not have the unit of force per unit area, , {a) Stress (6) Strain, , {c) Young's modulus of elasticity (d) Pressure

Page 2 :
10., , 1k., , 12., , 15., , 16., , 17., , The reason for the change in shape of a regular body is, , {a) Volume stress (b) Shearing strain (c) Longitudinal strain (d) Metallic strain, When a spiral spring is stretched by suspending a Joad on it, the strain produced ts called, , (a) Shearing {b) Longitudinal (c) Volume ({d) Transverse, The longitudinal strain is only possible in, , (a) Gases (b) Fluids (c) Solids (d) Liquids, , The face EFGH of the cube shown in the figure is displaced 2 mm parallel to itself when forces of, 5x10°N cach are applied on the lower and upper faces. The lower face is fixed The strain produced in, the cube is, , (a) 2, , {b) 0.5, , {c) 0.05, , (d) b2xtot, , Forces of 10°. each are applied in opposite direction on the upper and lower faces of a cube of side 10, cm, shifting the upper face parallel to itself by 0.5 cm. If the side of the cube were 20 cm, the, displacement would be, , , , (a) lem, , (b) 0.5 cm, {c) 0.25 cm, {d) 0.125 cm, The stress versus strain graphs for wires of (wo materials A und B are as shown in the figure. If Y.y and, Y» are the Young's modulii of the materials, then, , , , , , fa) ¥,=27,, (b) r-%, {c) Ty =3%,, (d) y,<3%,, The graph ts drawn between the applied force F and the strain (x) for a thin uniform wire. The wire, behaves as a liquid in the part, , , , (a) ab, {(b) be, {c) cd, (d) oa, ‘The diagram shows stress vs strain curve for the materials A and B. From the curves we infer that, , , , 3], , {a) A is brittle but B ts ductile i, (b) A is ductile and 8 is brittle, {c) Both A and B are ductile, , ‘Strain

Page 3 :
19., , 20., , 21, , 23., , {d) Both A and B are brittle, The figure shows the stress-strain graph of a certain substance. Over which region of the graph is, Hooke’s law obeyed, , (a) AB, (b) BC, {c) CD, {d) ED, Which one of the following is the Young’s modulus (in N/m?) for the wire having the stress-strain, curve shown in the figure, , , , , , {a) 24x10" a4, Ber, {b) 8.010! iil, {c) tox10" “o> 4 6 Rxt, {d) 29x10", , The adjacent graph shows the extension (A/) of a wire of length |m suspended from the top of a roof at, one end with a load W connected to the other end. If the cross sectional area of the wire is 10 hap, calculate the young’s modulus of the material of the wire, , {a) 2«10" Wtm*, , (b) 2510-8 Nb?, , te) det Nm?, , (d) 210-7 Nim?, , In the Young's experiment, if length of wire and radius both are doubled then the value of F will, become, , {a) 2 times (b) 4 times (c) Remains same (d) Half, , A rubber cord catapult has cross-sectional area 25mm” and initial length of rubber cord is 10cm. It is, stretched to Sem and then released to project a missile of mass Sgm Taking y,.., =5*10°W Jae, velocity of projected missile is, , {a) 20 ms! (b) 100 mis"! (c) 250 ms” (d) 200 ms", , Consider the following statements, , Assertion (A) : Stress ts the internal force per unit arca of a body, , Reason (R) : Rubber is more clastic than steel,, , Of these statements, , (a) Both A and 2 are true and the 2 1s a correct explanation of the A, , {b) Both A and & are true but the 2 is not a correct explanation of the 4, , {c) A is true but the 2 is false, , (d) Both 4 and R are false, , {e) A ts false but the 2 is true, , The area of cross-section of a steel wire (¥ - 20x10"! Vim?) 18.0.1 em, The force required to double its, length will be, {a) 2«10"N" {b) 210" (c) 2«10"N ({d) 210"

Page 4 :
27., , 3h, , A metal bar of length £ and area of cross-section A 1s clamped between two rigid supports. For the, material of the rod, its Young’s modulus is ¥ and coefficient of linear expansion is a@. If the, temperature of the rod ts increased by .v'c , the force exerted by the rod on the supports ts, , (a) YALAt (b) YA a@Ar (c) Hex (d) YorAL At, Which one of the following substances possesses the highest elasticity, {a) Rubber (b) Glass (c} Steel (d) Copper, , There are two wires of same material and same length while the diameter of second wire is 2 times the, diameter of first wire, then ratio of extension produced in the wires by applying same load will be, fa) lit {b) 2:1 (co) 1:2 (dj 41, , Consider the following statements, , Assertion (A) : Rubber ts more clastic than glass., , Reason (R) : The rubber has higher modulus of elasticity than glass., , Of these statements, , (a) Both A and 2 are true and the X 1s a correct explanation of the A, , {b) Both 4 and R are true but the R is not a correct explanation of the 4, , {c) A ts true but the £ is false, , {d) Both A and & are false, , {c) A ts false but the R is true, , The longitudinal extension of any elastic material is very small, In order to have an appreciable, change, the material must be in the form of, , {a) Thin block of any cross section () Thick block of any cross section, ({c) Long thin wire (d) Short thin wire, , In suspended type moving coil galvanometer, quartz suspension is used because, , (a) [tis good conductor of electricity (b) Elastic atter effects are negligible, {c) Young's modulus is greater (d) There is no elastic limit, , You are given three wires 4, B and C of the same length and cross section They are cach stretched by, applying the same force to the ends. The wire is stretched least and comes back to its original length, when the stretching force is removed. The wire B is stretched more than 4 and also comes back to tts, original length when the stretching force is removed. The wire C ts stretched most and remains stretched, even when stretching force ts removed The greatest Young's modulus of elasticity is possessed by the, matenal of wire, , {a) A {b) B (c) C (d) All have the same, elasticity, , The ratio of diameters of two wires of same material ts 1: L. The length of wires are 4» each. On, applying the same load, the increase in length of thin wire will be, , {a) n’ times {b) » times (c) 2n times (d) None of the above, , A wire of radius r, Young’s modulus ¥ and length / is hung from a fixed point and supports a heavy, metal cylinder of volume Fat its lower end, The change in length of wire when cylinder is immersed, , in a liquid of density pis in fact, {a) Decrease by 22, Yr, , bree, Yat?, , , , ({b) Increase by, , , , {c) Decrease by oe, , Vem, a) Yx

Page 5 :
36., , 37, , 39., , 40., , If the ratio of lengths, radii and Young's modulii of steel and brass wires in the figure are a, 6 and ¢, respectively. Then the corresponding ratio of increase in the lengths would be, , date, @, , ja caseaesbee, © oe, {c) = Brass, oS, , A uniform heavy rod of weight W, cross sectional area A and length £ is hung from a fixed support., , Young’s modulus of the material of the rod is Y, If lateral contraction is neglected, the elongation of, , the rod under its own weight 1s, WE., , Wh, fa) a {b) a (c), A constant force J) is applied on a uniform elastic string placed over a smooth horizontal surface as, shown in figure. Young's modulus of string is Y and arca of cross-section 1s S. The strain produced in, the string in the direction of force is, , s, , WL, , qay, , (d) Zero, , {a), (b) & a”, fi, {c), AY, {d) 3s, , A uniform rod of length £ has a mass per unit length 2 and area of cross section A. The elongation in, the rod is / due to its own weight if it ts suspended from the ceiling of a room. The Young’s modulus, of the rod is, , , , Dag! dg dst a, {a) 4a {b) a (c) a (d) “aL, , AB ts an iron wire and CD 1s a copper wire of same length and same cross-section. BD is a rod of, length 0.8 mt, A load G= 2kg-wt is suspended from the rod At what distance x from point B should the, load be = suspended = for =the = orod) sto, sremain’ sin’ sa ___ horizontal __ position, (Fp. UE RIDIN fe? Vg = 19.6 10 fo?), , {a)O lm, (b) 0.3 m, (c) OS m, {d} 0.7m, A slightly comecal wire of length L and end radii ri: and r is stretched by two forces F, # applied, parallel to length in opposite directions and normal to end faces. If Y denotes the Young’s modulus., then extension produced is, , (a) (by 2 (co) SL id) 22, mt my my Mir, , ‘The force constant of wire 1s X and its area of cross-section 1s 4. If the force # is applied on it then the, increase in its length wall be