A car moves at 12 m/s for 30.0 seconds. It then accelerates at 1.5 m/s2 for 8.00 seconds. Finally, it continues on at this top speed for another 12.0 seconds. Calculate the net
displacement during the whole time interval.

Over the first 30.0 s, the undergoes a displacement of

(12 m/s) * (30.0 s) = 360 m

Over the next 8.00 s, the car accelerates from 12 m/s to a top speed of

12 m/s + (1.5 m/s²) * (8.00 s) = 24 m/s

and over this time interval, it is displaced an additional

(12 m/s) * (8.00 s) + 1/2 (1.5 m/s²) * (8.00 s)² = 144 m

For the last 12.0 s, the car moves at a constant speed of 24 m/s to cover a distance of

(24 m/s) * (12.0 s) = 288 m

So the car's net displacement is 360 m + 144 m + 288 m = 792 m. (The net displacement is the same as distance in this case because the car moves in only one direction.)

hi there!

out of the two, (b) precision would be more reasonable.   however, both a and b could be pretty reasonable.

-awesomerepublic   : )