A woman walks in a straight line. The woman’s velocity t seconds after passing through a fixed point A on the line is v m s^-1. The graph of v against t consists of 4 straight line segments (see diagram). The woman is at the point B when t = 60. Find

1. the woman’s acceleration for 0 < t < 30 and for 30 < t < 40,
2. the distance AB,
3. the total distance walked by the woman.