A 2 kg object is moving west at 4 m/s. It takes 2.0 s to slow down to 2 m/s, still moving west. What is the change in momentum, ΔP, of the object?
a. 4.0 kg∙m/s, west
b. 4.0 kg∙m/s, east
c. 2.0 kg∙m/s, west
d. 2.0 kg∙m/s, east