Superposition of Wave Pulses

This lets you play around with the superposition of two wave pulses on a string. You can adjust the amplitude of each pulse using the sliders on the right side of each horizontal line. The bottom line represents the sum of the two pulses together. You can slide the 'Simulation Time' slider to watch how the sum of the wave pulses interact with each other as they move.
Can you adjust the settings so that... 1. ...the wave pulses add up to zero when they are located on top of each other? This is destructive interference. 2. ...the wave pulses add together to form a wave that is twice the amplitude of each pulse on its own? This is constructive interference.