A 2200 kg car traveling at 11.4 m/s collides with a 2680 kg car that is initially at rest at the stoplight. The cars stick together and move 2.60 m before friction causes them to stop. Determine the coefficient of kinetic friction betwen the cars and the road, assuming that the negative acceleration is constant and that all wheels on both cars lock at the time of impact.
2007-12-11 16:12:30 · 1 answers · asked by Kecin S 1 in Science & Mathematics ➔ Physics
Momentum is always conserved during collisions.
Initial momentum: ( 2200 kg ) ( 11.4 m / s ) + 0
Final momentum: ( 2200 kg + 2680 kg ) ( v )
Set these two expressions equal and solve for the unknown velocity.
Now the work done by friction is equal to μmg and is also equal to the change in kinetic energy of the system, so
1/2 m v² = μ m g
where the masses cancel, g is the local acceleration of gravity ( 9.8 m / s² ), v is the velocity you just found, and μ is the coefficient of friction you're looking for.
2007-12-11 16:23:42 · answer #1 · answered by jgoulden 7 · 1⤊ 0⤋