A 1500-kg car travels at 90 km/h along a straight concrete highway.?

Question

Faced with an emergency situation, the driver jams on the brakes, and the car skids to a stop. What will be the cars stopping distance for (1) dry pavement and (2) wet pavement?

Answer 1

To answer this you need the coefficient of kinetic friction for dry concrete and wet concrete.
These will be in the form of a unit-less u.
Then, using conservation of energy, the KE of the car will be dissipated as heat due to friction
.5*m*v^2=m*g*u*d
where d is the stopping distance, and g is gravity, 9.81 m/s^2
note that m divides out leaving
d=v^2/(2*g*u)

j