A car can decelerate at -4.40 m/s2 without skidding when coming to rest on a level road. What would be the magnitude of its deceleration if the road were inclined at 12° uphill? Assume the same static friction coefficient.

Answer 1

The friction force on the tires remains -4.40 m/s^2*M if tires are on the verge of slipping. Gravity will apply an additional retarding force of -M g sin 12 = 2.04 m/s^2*M

The resultant deceleration is
(-4.40 - 2.04) M/M
= -6.44 m/s^2

(mass M cancels out)