You are travelling in your car at 50km/hr, your friend is traveling at 25 km/hr, both have the same mass. What distance do you need to travel to stop compared to the distance that your friend needs to stop? How will the stopping distance change if you and your friend are driving on a slippery surface?
(a)
mv²/2=W(fr) =F(fr)s=μNs=μmgs
s= mv²/2μmg= v²/2μg
s is the same for the both cars
(b)
s↑ since μ↓