In the figure below, the driver of a car on a horizontal road makes an emergency
ID: 2099957 • Letter: I
Question
In the figure below, the driver of a car on a horizontal road makes an emergency stop by applying the brakes so that all four wheels lock and skid along the road. The coefficient of kinetic friction between tires and road is0.39. The separation between the front and rear axles is L = 4.1 m, and the center of mass of the car is located at distance d = 1.8 m behind the front axle and distance h = 0.70 m above the road. The car weighs 11 kN. Find the magnitude of the following. (Hint: Although the car is not in translational equilibrium, it is in rotational equilibrium.)
Explanation / Answer
(A)breakin force= 0.39*11000*4 accln=f/m=0.39*11000*4/11000=0.39*4=1.56m/s^2 (B)normal at rear wheel= n1 taking moment abt front wheel d*11000=2n1*l n1=1.8*11000/8.2 n1=2414.63 N (C)normal at front wheel=n2 considering force in verticl direction 2*(n1+n2)=11000 n2=5500-2414.63 n2=3085N (D) breaking force on each rear wheel be fr fr=.39*n1=.39*2414.63= 941.7N (E) breaking force on each front wheel be ff ff=.39*n2=.39*3085=1203 N