What was the speed of the second car when it hit the first one?

[samdiah]

A car with mass of 1875kg is traveling along a country road when the driver sees a deer dart out unto a road. The driver slams on the brakes and manages to stop before hitting the deer. The driver of second car (mass 2135kg) is driving too close and doesn't see the deer. When the driver realizes car before him stopping he slams the brake to stop but isn't able to. The cars locks together and skid another 4.58 m. All of the motion is along straight line. If coefficeint of friction between tire andasphalt is 0.750, what was speed of seconf car when it hit the first one?

answer:
I am not very sure at all, but I think that this is wut I should do:

since momentum is equal mv + mv =v (m+m)

Then E=f*d
=mg*4.58

f=uN

 

[civil_dude]

Should work. Plug and chug.

 

[samdiah]

Doesn't Work!

 

[OlderDan]

A car with mass of 1875kg is traveling along a country road when the driver sees a deer dart out unto a road. The driver slams on the brakes and manages to stop before hitting the deer. The driver of second car (mass 2135kg) is driving too close and doesn't see the deer. When the driver realizes car before him stopping he slams the brake to stop but isn't able to. The cars locks together and skid another 4.58 m. All of the motion is along straight line. If coefficeint of friction between tire andasphalt is 0.750, what was speed of seconf car when it hit the first one?

answer:
I am not very sure at all, but I think that this is wut I should do:

since momentum is equal mv + mv =v (m+m)

Then E=f*d
=mg*4.58

f=uN

You have different m and different v all represented by the same letter. You need to distiquish between two different masses and three different velocities. You also need to use the coefficient of friction to find the frictional force.