(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known dataCar A has a mass of 1900 kg and crashes into parked Car B with a mass of 1100 kg. Car A claims to have hit the brakes 15 metres before crashing into Car B. After the collision, Car A slid an additional 18 metres while pushing Car B 30 metres from its parked position. The coefficient of friction is .6 between the locked tires and the road. Prove that Car A was speeding. Legal speed limit of the road is 90 km/h.

2. Relevant equations

F=ma

W=[tex]\Delta[/tex]KE

KE=.5 x mv[tex]^{2}[/tex]

F[tex]_{net}[/tex]=F[tex]_{horizontal}[/tex]-F[tex]_{friction}[/tex]

F[tex]_{friction}[/tex]=[tex]\mu[/tex]mg

3. The attempt at a solution

I set force friction equal to the force of motion, and got that to be 11400 Newtons. Then I plugged that into the equation for work, and used 18m as the displacement, and 0 for the final velocity, and solved for the initial velocity. I got 14.697 m/s as that answer. Then I used the equation for work again, but this time I used 14.697 m/s as the final velocity, and found the initial velocity to be about 6 m/s. However, I don't think it's right, since I didn't use anything about Car B. I'm not sure exactly what to do with it.

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# Homework Help: Energy [Car collisions]

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