Interference of rectangular pulse

[sapiental]

Question Details:
The figure shows two rectangular wave pulses
traveling toward each other on a stretched string.
Each pulse is traveling with a speed of 1.00 mm/s,
and has the height and width shown in the figure.
If the leading edges of the pulses are 8.00 mm
apart at t = 0, sketch the shape of the string at
t = 4.00 s, t = 6.00 s, and t = 10.0

you guys don't have to sketch the result for me but please be as descriptive as possible.

Im thinking that at t = 4s the 2 pulses will meet. If the pulses were of equal amplitude the string would be at equilibrium. But the right one is 4.00mm so I think it will look something like a upward pulse with 1.00mm amplitude and 4.00mm width?

At t = 6s the pulses will be 4mm apart. One pulse traveling in the negative x direction with an amplitude of 4mm and width 4mm and velocity 1mm/s. The second pulse traveling in the positive x direction with amplitude 3mm, width 4mm, and velocity 1mm.

not sure about t = 10s, but i think the problem wants us to presume that the pulses reflect off the wall..

Any help is much appreciated. And could you guys also explain how you got your answers.. i.e. by what rules etc. tho one I can think of is the principle of superposition (y(x,t) = y1(x,t) + y2(x,t). thanks

Please see the attached pic for the diagram.

 

[berkeman]

You have the right idea -- just add them with superposition. Where is the wall you are referring to?