A composite rod is made by joining a copper rod, end to end, with a second rod of different material but of the same area of cross section. At `25^(@)C`, the composite rod is `1 m` long and the copper rod is `30 cm` long. At `125^(@)C` the length of the composte rod increases by `1.91 mm`. When the composite rod is prevented from expanding by bolding it between two rigid walls, it is found that the constituent reds have remained unchanged in length in splite of rise of temperature. Find yong's modulus and the coefficient of linear expansion of the second red (Y of copper `=1.3xx10^(10) N//m^(2)` and `a` of copper `=17xx10^(-6)//K`).

Explanation

To solve the problem step-by-step, we will analyze the composite rod made of copper and a second material. We will use the given data to find the Young's modulus and the coefficient of linear expansion of the second rod.

### Step 1: Understand the Problem
We have a composite rod consisting of:
- A copper rod of length \( L_{Cu} = 0.3 \, m \)
- A second rod of length \( L_{R} = 0.7 \, m \) (since the total length is \( 1 \, m \))

The temperature change is from \( 25^\circ C \) to \( 125^\circ C \), which gives us:
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