Two waves, both of amplitude A, are traveling in opposite directions along a rope. What is the range of displacement y that the two waves may cause when they overlap?

-2A <= y <= 2A
-A <= y <= A
-1/2A <= y <= 1/2A
0<= y <= A

A scientist rings a bell to study sound waves in a room. Which action will decrease the effect of overlapping sound waves in the room?
Lining the walls with material that reflects sound waves
Lining the walls with material that absorbs sound waves
Ringing several bells, each of different size
Ringing several identical bells at different times.

In a sinusidal standing wave, a node forms where superstition consistently causes______.
Maximum amplitude
Amplitude of one half maximum
Amplitude of one half the wavelength
Zero amplitude
Please help!