Problem $1$ Snapshots and History

$($a$)$ A snapshot of two pulses on a string are shown at $t=0,$ both have equal and opposite speed of $1\frac{m}{s}.$ Draw a snapshot $(y$ versus $x)$ for the times $t=2s$ and $t=3s.($b$)$ For the same two pulses sketch a history plot $(y$ versus $t)$ for the position $x=4m$ from $($at least$)t=0$ to $t=4s.($c$)$ Consider the snapshot $($at $t=0)$ of the pulse on the string to the lower$-$right now. The right end is tied down so that it cannot move at $x=3m.$ Draw a snapshot of the string at $t=1\mathrm{.}25s,t=1\mathrm{.}5s,t=1\mathrm{.}75s,$ and $t=2\mathrm{.}0$ s$.$