A girl riding a bicycle with a speed of 5 m/s towards north direction, observes rain falling vertically down. If she increases her speed to 10 m/s, rain appears to meet her at 45° to the vertical. What is the speed of the rain? In what direction does rain fall as observed by a ground based observer?
(Hint: Assume north to be cap i direction and vertically downward to be - cap j . Let the rain velocity vr be a cap i + b cap j . The velocity of rain as observed by the girl is always vr - vrgirl . Draw the vector diagram/s for the information given and find a and b. You may draw all vectors in the reference frame of ground based observer.)