Question

Two pulses in a stretched string whose centers are initially $8cm$ apart are moving towards each other as shown in the figure. The speed of each pulse is $2cm/s$. After $2$ seconds, the total energy of the pulses will be

• A. Zero
• B. purely kinetic
• C. purely potential
• D. partly kinetic and partly potential

Answer 1

The correct option is B purely kinetic

After $2seconds,$ the pulses overlap each other completely and as a result, the string is straight and therefore does not have any potential energy and its entire energy must be kinetic energy.