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:

the total distance that martina travels that day is

(distance from home to mom's office) plus (distance from mom's office to school)

plus (distance from school to library) plus (distance from library to friend's house)

plus (distance from friend's house to martina's house).

(we don't know what any of these distance actually is.)

if the person is shown to have +90n, then ans is -10n.

if the person is shown to have -90n, then ans is +10n.