A car moves along a straight road with velocity v(t) (measured in m/s) described as follows:
• v(t) increases linearly from 0 at t=0 s to 18 at t=3 s.
• v(t) then decreases linearly to −6 at t=7 s.
• v(t) remains constant at −6 for 7≤t≤9 s.
Compute the net displacement of the car for 0≤t≤9 s. Include appropriate units.