The Young's modulus of steel is twice that of brass. Two wires of the same length and of the same area of cross-section, one of steel and another of brass are suspended from the same roof. If we want the lower ends of the wires to be at the same level, then the weight added to the steel and brass wires must be in the ratio of:

1.	1:2	2.	2:1
3.	4:1	4.	1:1

The following four wires are made of the same material. Which of them will have the largest extension when the same tension is applied?

(1) Length=50 cm, diameter=0.5 mm 

(2) Length=100 cm, diameter=1 mm 

(3) Length=200 cm, diameter=2 mm 

(4) Length=300 cm, diameter=3 mm 

When a certain weight is suspended from a long uniform wire, its length increases by one cm. If the same weight is suspended from another wire of the same material and length but having a diameter half of the first one, then the increase in length will be -

(1) 0.5 cm                             

(2) 2 cm

(3) 4 cm                                 

(4) 8 cm

The material which practically does not show elastic after effect is 

(1) Copper                         

(2) Rubber

(3) Steel                             

(4) Quartz

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:

The relationship between Young's modulus Y, Bulk modulus K and modulus of rigidity n is

(1) $Y=\frac{9nK}{n+3K}$                                    

(2) $\frac{9YK}{Y+3K}$ 

(3)  $Y=\frac{9nK}{3+K}$                                     

(4) $Y=\frac{3nK}{9n+K}$         

The Young's modulus of a rubber string 8 cm long and density $1.5 kg/m^3$ is $5\times {10}^8 N/m^2$, is suspended on the ceiling in a room. The increase in length due to its own weight will be

(1) $9.6\times {10}^{-5} m$                           

(2) $9.6\times {10}^{-11}m$

(3) $9.6\times {10}^{-3} m$                           

(4) 9.6 m

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

(1) Equal to that on A

(2) Four times that on A

(3) Two times that on A               

(4) Half that on A

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

(1) Half                                 

(2) Same

(3) Double                             

(4) One fourth

Why the spring is made up of steel in comparison of copper?

(1)   Copper is more costly than steel

(2)   Copper is more elastic than steel

(3)   Steel is more elastic than copper

(4)   None of the above