Is it right to count 120 km eastward as + 120 km eastward and 80 km westward as - 80 km?

Is it right to count 120 km eastward as + 120 km eastward and 80 km westward as - 80 km?

If it is 120km eastward and 80km westward, then it is + 20km

On the Shanghai Nanjing Expressway, a car was driving at a constant speed of 108km / h. The driver suddenly found that there was an emergency ahead. After 0.6s, he began to brake, and after 4.4S, he taxied 52m, and the car stopped. The average speed of the driver from finding the situation to stopping was______ ．

∵ v = 108km / h = 30m / s, ∵ 0.6s the distance of the car is s = VT = 30m / s × 0.6s = 18m; the distance of the car from finding the situation to stopping is s' = S + s sliding = 18m + 52m = 70m; the time used is t '= t + T sliding = 0.6s + 4.4S = 5S; the average speed from finding the situation to stopping is v' = s' = 70m5s = 14m / S; so the answer is: 14m / s

If the speed of a car on the highway is 108km / h and the diameter of the wheel is 60cm, the speed of the wheel is () rad / h
Please pay attention to the unit

108*1000/(3.14*2*0.6)=28662.42

The power of a Santana car is 66kw, and the maximum speed limit on the highway can reach 30m / s
(1) How many joules does the car do per hour?
(2) What is the minimum traction of a car on the highway?

According to the formula P = w / T = (66 × 1000) / (60 × 600) = 55 / 3j
(2) P=Fv
F=P/v=66000/30=2200N