Convert values to consistent units:
66 mi/h = 66 mi/h *5280 ft/mi ÷ 3600 s
= 96.8 ft/s
similarly
55 mi/h = 80.67 ft/s
acceleration = -14 ft/s²
Time required=(80.67-96.8)/(-14)
= 1.15 s
Do not forget to add the reaction time, which could exceed the mechanical deceleration time.
The brakes on your automobile are capable of creating acceleration of 14 ft/s2. If you are going 66 mi/hr and suddenly see a state trooper, what is the minimum time required to get your car to 55 mi/hr?
1 answer