A pulse travelling on a string is described by the function y =...

The equation of the pulse is $y = \dfrac{a^3}{(x - vt)^2 + a^2}$.

The peak of the pulse occurs where the displacement $y$ is maximum. This happens when the denominator is minimum, which corresponds to $(x - vt)^2 = 0$.

Thus, the position of the peak at any time $t$ is given by $x = vt$.

Given the velocity of the pulse $v = 20 \text{ cm s}^{-1}$.

At $t = 0$, the position of the peak is $x = 20 \times 0 = 0$.

At $t = 1 \text{ s}$, the position of the peak is $x = 20 \times 1 = 20 \text{ cm}$.

At $t = 2 \text{ s}$, the position of the peak is $x = 20 \times 2 = 40 \text{ cm}$.