Question

A large 75-kg lighting fixture can be hung from wires of identical size and shape made of aluminum, brass, or copper. The values of Young's modulus for these metals are 0.70 × 1011 Pa (aluminum), 0.91 × 1011 (brass), and 1.1 × 1011 (copper). Which wire would stretch the least distance?A. AluminumB. BrassC. CopperD. They will all stretch the same distance

Answer 1

C. Copper

Step-by-step explanation:

F = Force on string

`L_0` = Intial length of string

A = Area of string

E = Young's modulus of material

Change in length is given by

`\Delta L=(FL_0)/(AE)`

It can be seen that the change in length is inversely proportional to the Young's modulus of the material.

Here

`E_a=0.7* 10^(11)\ Pa`

`E_b=0.91* 10^(11)\ Pa`

`E_c=1.1* 10^(11)\ Pa`

`\\\Rightarrow E_c>E_b>E_a`

So, copper will stretch the least.