Q. 26 A mass of 2 kg is suspended with thread AB (figure). Thread CD of the same type is attached to the other end of 2 kg mass. The lower thread is pulled gradually, harder and harder in the downward direction, so as to apply force on AB. Which of the threads will break and why?

Hint: Tension in string AB is more than that in string CD.
Step 1: Interpret the variation in tension.
 

The thread AB will break earlier than the thread CD. This is because forces acting on thread CD = applied force and force acting on thread AB (applied force + weight of 2 kg mass). Hence, the force acting on thread AB is Érger than the force acting on thread CD.