An aluminum rod is 10.0 cm long and a steel rod is 80.0 cm long when both rods are at a temperature of 29°C. The increase in the length of the joined rod, in mm is closest to:

Question

The coefficients of linear expansion of aluminum and steel are 2.4*10^-5 K⁻¹ and 1.2*10^-5 K⁻¹ respectively. Both rods have the same diameter. The temperature is raised to 79°C.

Answer 1

Remember that a change in temperature in ^oC is the same change in Kelvin.

The formula for the final temperature is L=l_a(1+α_aΔT)+l_s(α_sΔT)

where ΔT=79-25=54 and the other quantities needed are given.

Note the coefficients are unitless so the units should be consistent. Let me know if you got the answer.