An automobile of mass 1000kg is initially travelling eastward at 20ms−1. After applying the brakes and making a U-turn, it moves westward at 10ms−1.
(i) Taking the east as the positive x-direction, calculate the change in linear momentum of the automobile.
(ii) How large is the impulse delivered to the automobile during the manoeuvre?
(iii) If, instead, the west were chosen as the positive x-direction, what numerical value would you obtain for the change in momentum? Comment briefly on the physical significance of any difference in sign.