A series of pulses of amplitude 0.25 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.

0m

Explanation:

since the string is rigidly attached to the post, the reflected and incident pulses are of the same amplitude but different polarities. At the point where the two pulses meet, the amplitude will be the addition of that of the incident and the reflected pulses. i.e Amplitude= 0.25 + -0.25=0m

it becomes positively charged by charging it

vapour or gas assuming atmospheriv pressure