Compared to 15 mph on a dry road, about how much longer will it take for

you to stop at 30 mph on a snow-covered road?

2 to 3 times

4 to 6 times

8 to 10 times

8 to 10 times

Explanation:

For dry road

u = 15 mph (1 mph = 0.44 m/s)

u = 6.7 m/s

Let take coefficient of friction (μ) of dry road is 0.7

So the de acceleration a = μ g

a = 0.7 x 10 m/s ² (g=10 m/s ²)

a = 7 m/s ²

We know that

v = u - a t

Final speed, v=0

0 = 6.7 - 7 x t

t = 0.95 s

For snow road

μ = 0.4

de acceleration a = μ g

a = 0.4 x 10 = 4 m/s ²

u = 30 mph = 13.41 m/s

v = u - a t

Final speed, v=0

0 = 30 - 4 x t'

t'=7.5 s

t'=7.8 t

We can say that it will take 8 to 10 times more time as compare to dry road for stopping the vehicle.

8 to 10 times