You make two wave pulses. The first wave pulse is made going up. The second wave pulse is made going down. Both waves have the same amplitude. The first wave hits a fixed boundary. What will happen when the two waves overlap? You make two wave pulses. The first wave pulse is made going up. The second wave pulse is made going down. Both waves have the same amplitude. The first wave hits a fixed boundary. What will happen when the two waves overlap? the waves amplitude will double the waves amplitude will half the waves amplitude will be zero (cancel out) the pulses remain the same