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

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

The Young's modulus of a rubber string 8 cm long and density $1.5<mspace\; width="1em"></mspace>kg/m^3$ is $5\times {10}^8<mspace\; width="1em"></mspace>N/m^2$, is suspended on the ceiling in a room. The increase in length due to its own weight will be

1. $9.6\times {10}^{-5}<mspace\; width="1em"></mspace>m$                           

2. $9.6\times {10}^{-11}m$

3. $9.6\times {10}^{-3}<mspace\; width="1em"></mspace>m$                           

4. 9.6 m

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:

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

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

The material which practically does not show elastic after effect is 

1. Copper                         

2. Rubber

3. Steel                             

4. Quartz

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. $Y=\frac{3nK}{9n+K}$         

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