Wave Motion 5 Question 3
3. Two pulses in a stretched string, whose centres are initially $8 cm$ apart, are moving towards each other as shown in the figure. The speed of each pulse is $2 cm / s$. After $2 s$ the total energy of the pulses will be
(2001, 2M)
(a) zero
(b) purely kinetic
(c) purely potential
(d) partly kinetic and partly potential
Show Answer
Answer:
Correct Answer: 3. (b)
Solution:
- After two seconds both the pulses will move $4 cm$ towards each other. So, by their superposition, the resultant displacement at every point will be zero. Therefore, total energy will be purely in the form of kinetic. Half of the particles will be moving upwards and half downwards.
