Questions

We know that,

The equivalent K =  L1 + L2L1K1+L2K2

where L1 & L2 are plate1 & Plate2 thicknesses, K1 & K2 are coefficient thermal conductivity of plate1 & Plate2 respectively.

But here L1 = L2 = L (say)

Then K = L+L/(L/K1 + L/K2)  =  2K1K2K1+K2

This is a common error while compiling C program in Linux. This error occurs when you are using pthread_create function to create threads in your programs.

To fix this problem ensure following points:
Include header file pthread.h in your program.
Add –lpthread linker flag with compilation command.
1- Include Header file
#include <stdio.h>
#include <pthread.h>
...
...
2- Compile command
gcc main.c -o main -lpthread

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