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An SUV and a car collide at a stoplight. The wreck slides to a complete stop.

mass SUV = 4200 kg

mass car = 2100 kg

velocity car = 0 m/s

distance the wreck slides = 12 meters

Mu = .65

Find the velocity of the SUV.

What I tried:

Since it crash is shown as being completely inelastic I know that both objects have the same velocity after the crash so I can treat their mass as one also.

First I set up an equation for the momentum:

p1 + p2 = p1 (prime) + p2 (prime)

[mass SUV * velocity SUV] + [mass car + velocity car] = vprime [mass SUV + mass car]

[4200 * velocity SUV] + 0 = 6300v(prime)

So from that equation I have two unknowns.

I know that the final velocity of the wreck is 0 and that the initial velocity before the slide is the same as Vprime.

The full body diagram that I drew for the wreck just before the slide has four forces acting upon the mass: Fg down, Fn up, the momentum to the right, and friction to the left.

After doing that I'm not sure where to go next.

Any ideas?