Question

A 1890 kg car traveling at 13.3 m/s collides with a 2970 kg car that is initally at rest at a stoplight. The cars stick together and move 1.96 m before friction causes them to stop. Determine the coefficient of kinetic friction between the cars and the road, assuming that the negative acceleration is constant and all wheels on both cars lock at the time of impact.

A 1890 kg car traveling at 13.3 m/s collides with a 2970 kg car that is initally at rest at a stoplight. The cars stick together and move 1.96 m before friction causes them to stop. Determine the coefficient of kinetic friction between the cars and the road, assuming that the negative acceleration is constant and all wheels on both cars lock at the time of impact. Submit Answer e Post Discussion * Send Feedback

Answer 1

By Conservation of momentum

m₁V₁+m₂V₂=(m₁+m₂)V

1890*13.3+2970*0=(1890+2970)V

V=5.1722 m/s

From Kinematic equation

V²=V_o²+2ad

Since car is decelerating and coming to stop means V=0

0=5.1722²+2*(-a)*1.96

a=26.75/3.92=6.824 m/s²

from newtons second law

F=ma

u_kmg=ma

=>u_K=a/g =6.824/9.8 =0.696