A car traveling at 35 mi/h is to stop on a 35-m long shoulder of the road. ?

Question

a. what is the required magnitude of the minimum acceleration?

b. how much time will elapse during this minimum deceleration until the car stops?

Answer 1

a. Convert mi/hr into m/s by multiplying by 0.44704.

a = (vf² - vi²) / 2d

= ((0 m/s)² - (16 m/s)²) / (2 x 35 m)

= - 3.6 m/s²

b. t = (vf - vi) / a

= (0 m/s - 16 m/s) / (- 3.6 m/s²)

= 4.4 s