Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$ .
Assertion $A$ : When a rod lying freely is heated, no thermal stress is developed in it.
Reason $R$ : On heating, the length of the rod increases.
In the light of the above statements, choose the correct answer from the options given below:

Question

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$ .

Assertion $A$ : When a rod lying freely is heated, no thermal stress is developed in it.

Reason $R$ : On heating, the length of the rod increases.

In the light of the above statements, choose the correct answer from the options given below:

Aicharya · Accepted Answer

Thermal stress is mechanical stress created by any change in temperature of a material. When the body is under some constraints, thermal stress is generated. But if it is lying freely, no thermal stress is developed.

The increase in length of a body with temperature is given by

$∆ L = L α ∆ T$

So, with the increase in temperature, the length of the rod increases.

$A$ and $R$ are true but $R$ is not the correct explanation of $A$ .

Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R .…

Solution