Question

Two steel rods and copper rod of equal length $l_0$ and equal cross-sectional are joined rigidly as shown. All the rods are in a state of zero tension at $0^{\circ }C$ . The temperature of system increase up to ${30}^{\circ }C$ , then :

• A. tensile force on either steel plate is half of copper plate
• B. the net expansion in copper plate is less than the thermal expansion of the copper plate
• C. the expansion in either steel plate is larger then thermal expansion in steel plates
• D. all of the above

Answer 1

The correct option is D all of the above

So, The coefficient of linear expansion of copper is larger than that of steel. So, the change in natural length of copper is larger than that of steel due to rise of temp but rods are rigidly fixed. So final change in the length of all rods is same. It means stress produced in rods decreases the length of copper and increases the length of steel. So tensile stress acts on the steel rod and compressive force acts on the copper rod.