This is the assignment for the practice of objective questions of mechanical properties of solids. Students can consider it as a test paper of the chapter mechanical properties of solids.
1. Breaking stress depends on (a) length of wire (b) Area of cross-section of wire (c) both a and b (d) independent of length and area of cross-section.
2.Which of the following is perfectly plastic? (a) plasticine (b) Quartz fibre (c) steel (d) Rubber.
3. the length of an elastic string is X meter when the tension is 8N and Y m when tension is 10N , what will be the length when tension is 18N . (a) 4X-5Y (b) 5Y-4X (c) 9X-4Y (d) 4Y-9X.
4. When a load of 10kg is hung in the wire, then extension of 2m is produced. Then work done by the restoring force is (a)200J (b) 100J (c) 50J (d) 25J .
5.Substance which can be elastically stretched to large value of strain is called (a) isomers (b) isodiapheres (c) Plastomers (d) Elastomers .
6. A force F doubles the length of the wire of cross-section a . Then the Young’s modulus of the wire is (a) F/a (b) F/3a (c) F/2a (d) F/4a .
7. Breaking stress of a material is 2×108 N/m2, what maximum length of the wire of this material can be taken so that the wire doesn’t break by own weight? ( density of material is 5×103kg/m3) (a) 1km (b)2km (c) 3km (d) 4km.
8.Young modulus of elasticity for a gas is (a) 1 (b) infinity (c) zero (d) none of these .
9. If we added an impurity in the material then its elasticity (a) may change (b) never change (c) remain the same (d) change by a factor of 5 .
10. A structural steel rod has a radius r = 10mm when a force 100 kN is applied . it stretches along its length Y for steel is 2x 1011 N/m2 . aswer the following questions-
(i) what is the stress produced ?
(ii)what is the elongation produced ?
(iii) what is the elastic energy density of the steel rod ?
(iv) elastic potential energy stored in the rod is what?
11.Elasticity of a rigid body is ………..
12. If Young’s modulus is three times of modulus of rigidity. Then the Poisson’s ratio is equal to …………
13. In case of bending of a beam , depression depends on the Young’s modulus Y as proportional to …….
14.The stress strain graph for two materials A and B are shown in fig. (a) Which one has greater Young’s modulus ?(b) which one is strongest material?(c) which is more ductile?(d) which is more brittle?
Answers-
1.-d 2.-a 3.-b 4.-b 5.-d 6.-a 7.-d 8.-c 9.-a 10.- (a) 3.18X108Pa (b)1.59mm (c) 2.5×105j/m3 (d)7.92 J . 11.- infinity 12.- 0.5 13.- Y-1 .