1. The material which practically does not show elastic after effect is

a) Copper

b) Rubber

c) Steel

d) Quartz

Explanation: Quartz

2. If the temperature increases, the modulus of elasticity

a) Decreases

b) Increases

c) Remains constant

d) Becomes zero

Explanation: Because due to increase in temperature intermolecular forces decreases.

3. A force F is needed to break a copper wire having radius R. The force needed to break a copper wire
of radius 2R will be

a) F/2

b) 2F

c) 4F

d) F/4

Explanation:

4. The relationship between Young's modulus Y, Bulk modulus K and modulus of rigidity \[\eta\] is

a) \[Y=\frac{9\eta K}{\eta+3 K}\]

b) \[Y=\frac{9Y K}{Y+ 3K}\]

c) \[Y=\frac{9\eta K}{3+ K}\]

d) \[Y=\frac{3\eta K}{9\eta+ K}\]

Explanation:

5. The diameter of a brass rod is 4 mm and Young's modulus of brass is \[9\times10^{10}N\diagup m^{2}\] . The force
required to stretch by 0.1% of its length is

a) \[360\pi N\]

b) 36 N

c) \[144\pi \times10^{3} N\]

d) \[36\pi \times10^{5} N\]

Explanation:

6.If x longitudinal strain is produced in a wire of Young's modulus y, then energy stored in the
material of the wire per unit volume is

a) \[yx^{2} \]

b) \[2yx^{2} \]

c) \[\frac{1}{2}y^{2}x \]

d) \[\frac{1}{2}yx^{2} \]

Explanation:

7. In a wire of length L, the increase in its length is l. If the length is reduced to half, the increase in
its length will be

a) l

b) 2l

c) \[\frac{l}{2}\]

d) None of the above

Explanation:

8. The Young's modulus of a rubber string 8 cm long and density \[1.5 kg\diagup m^{3} \] is \[5\times10^{8} N\diagup m^{2} \] , is
suspended on the ceiling in a room. The increase in length due to its own weight will be

a) \[9.6\times10^{-5} m\]

b) \[9.6\times10^{-11} m\]

c) \[9.6\times10^{-3} m\]

d) 9.6 m

Explanation:

9. A and B are two wires. The radius of A is twice that of B. They are stretched by the some load.
Then the stress on B is

a) Equal to that on A

b) Four times that on A

c) Two times that on A

d) Half that on A

Explanation:

10. If the length of a wire is reduced to half, then it
can hold the ......... load

a) Half

b) Same

c) Double

d) One fourth

Explanation: Breaking force \[\propto\] Area of cross section of wire i.e. load hold by the wire does not depend upon the length of the wire.