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QJEEM23Ph9a8e: JEE Main 2023 Physics - Class 11 JEEM23Ph9a8e Solution: The length of a wire becomes and when and tensions are applied…

The length of a wire becomes l1l_{1} and l2l_{2} when 100 N100 \mathrm{~N} and 120 N120 \mathrm{~N} tensions are applied respectively. If 10 l2=11 l110 ~l_{2}=11~ l_{1} , the natural length of wire will be 1x l1\frac{1}{x} ~l_{1} . Here the value of xx is _____________.

Step-by-Step Verified Solution

Given:

  1. When tension T1=100 NT_1 = 100 \mathrm{~N} , extension =l1−l0= l_1 - l_0 .
  2. When tension T2=120 NT_2 = 120 \mathrm{~N} , extension =l2−l0= l_2 - l_0 .

Now, let's write the equations using Hooke's Law:

100=k(l1−l0)100 = k(l_1 - l_0)

120=k(l2−l0)120 = k(l_2 - l_0)

Divide the first equation by the second equation:

56=l1−l0l2−l0\frac{5}{6} = \frac{l_1 - l_0}{l_2 - l_0}

Given the relationship between l1l_1 and l2l_2 :

10l2=11l110l_2 = 11l_1

Now, let's solve for l0l_0 :

5l2−5l0=6l1−6l05l_2 - 5l_0 = 6l_1 - 6l_0

l0=6l1−5l2l_0 = 6l_1 - 5l_2

Substitute the relationship between l1l_1 and l2l_2 :

l0=6l1−5(11l110)l_0 = 6l_1 - 5\left(\frac{11l_1}{10}\right)

l0=6l1−11l12l_0 = 6l_1 - \frac{11l_1}{2}

l0=l12l_0 = \frac{l_1}{2}

Therefore, the natural length of the wire is 1xl1=21l1=2l1\frac{1}{x}l_1 = \frac{2}{1}l_1 = 2l_1 .

The value of xx is 22 .

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