Question

Figure (15-E7) shows two wave pulses at t = 0 travelling on a string in opposite directions with the same wave

speed $50cm{s}^{-1}.$ Sketch the shape of the string at t = 4 ms, 6 ms, 8 ms, and 12 ms.

Answer 1

The distance travelled by the pulses are shown below.

$t=4ms=4\times {10}^{-3}s,$

$s=vt=50\times {10}^{-2}\times 4\times {10}^{-3}$

$=2mm$

$t=8ms=8\times {10}^{-3}s,$

$s=vt=50\times {10}^{-2}\times 8\times {10}^{-3}$

$=4mm$

$t=6ms=6\times {10}^{-3}s,$

$s=50\times {10}^{-2}\times 6\times {10}^{-3}$

$=3mm$

$t=12ms$

$=12\times {10}^{-3}s,$

$s=50\times {10}^{-2}\times 12\times {10}^{-3}$

$=6mm$

The shape of the string at different times are shown in the figure.