Question

On the interstate, the speed limit is 60 mi/h (about 100 km/h) a skilled driver can safely decelerate at about 6.1m/s^2. How long would it take to stop the vehicle? What would the total stopping distance be?

Answer 1

Answer:

4.56 seconds

63.25 m

Explanation:

t = Time taken for the car to stop

u = Initial velocity = 60 km/h = 100 km/h = 100000/3600 = 27.78 m/s

v = Final velocity = 0

s = Displacement

a = Acceleration = -6.1 m/s²

Time taken by the car to stop

$v=u+at\\\Rightarrow t=\frac{v-u}{a}\\\Rightarrow t=\frac{0-27.78}{-6.1}\\\Rightarrow t=4.56\ s$

Time taken by the car to stop is 4.56 seconds

$s=ut+\frac{1}{2}at^2\\\Rightarrow s=27.78\times 4.56+\frac{1}{2}\times -6.1\times 4.56^2\\\Rightarrow s=63.25\ m$

The total stopping distance would be 63.25 m