question_answer

A block of mass M is supported by a cord C from a rigid support, and another cord D is attached to the bottom of the block. If you give a sudden jerk to D, it will break. But if you pull on D steadily, chord C will break. Why?

Answer:

                When a sudden jerk is given to D, the upper portion of the system is not able to share the force in short time and the block tends to remain at rest (inertia of rest). So the chord D breaks. When the chord D is pulled steadily, the force gets sufficient time to reach the chord C which ultimately breaks.