”Braking distance” math 應用題

"Braking distance"
‘Braking distance’ refers to the distance d m travelled by a vehicle before coming to a stop after applying the brake.
After several trials, it is found that braking distance can be obtained by the following formula:
d =
v^2 (V的2次方，條橫線系分數個條線，即是v^2 over 20k)
20k

where v m/s is the speed of the vehicle when the brake is just applied and k is a specific value.

(a) Express the speed of 43.2 km/h of a vehicle in m/s.
(b) When the weather is good, k is 0.6. Complete the following table.
Speed(km/h) Braking distance (m)
43.2 ?
54 ?
97.2 ?
(c) A driver is driving at a speed of 54 km/h and he applies the brake immediately after he notices an object in front of him. The distance between the vehicle and the object at that moment is 20m.
(i) If he is driving in a good weather condition, determine whether the vehicle will crash into the object.
(ii) If he is driving in a rainy day, where k is 0.55, determine whether the vehicle will crash into the object.