High school physics funny topic question bank

On a sunny day, v= 108km/h=30m/s, so the reaction time of 1s goes by s 1=30m. Braking acceleration a = v02/2s = 302/(2 * (120-30)) = 5m/s2.

The friction coefficient in rainy days is 2/5 of the original, and the braking acceleration in rainy days is 2m/s 2.

Set the maximum speed v' in rainy days and the driving time V'* 1=V'. Braking distance s' = v' 2/2a = v' 2/4.

Then v'+v' 2/4 = 120, and V'=20m/s is obtained.

That is, the maximum speed in rainy days is 20m/s.