A series of pulses of amplitude 0.1 m are sent down a string that is attached to a post at one end. The pulses are reflected at the post and travel back along the string without loss of amplitude. What is the amplitude at a point on the string where two pulses cross if the string is rigidly attached to the post? Answer in units of m.

(a) if the string is rigidly attached to the post it means that the reflected wave is upside down from the original. Thus they add to zero when they cross.

(b) if the string is freely attached to the post it means the reflected wave is rightside up. Thus when they cross the amplitudes add so 0.10 + 0.10 = 0.2 m.

Explanation:

as we know our atmosphere or air have different levels. every level has other gasses, and every gas has another permeability. when the light comes from lower permeability to higher permeability, it changes its direction. so that means that when the light comes from the moon to the earth, it changes it's direction many more times. it basically means that the shape of the light part of the moon is changed on the earth.

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im srry but ur wrong the answer is d a smooth rock, some red dirt, and an empty bird's nest.