Trailing Car: Separation & Speed Calculations

[josh84]

Homework Statement

You are arguing over a cell phone while trailing an unmarked police car by 25m; both your car and the police car are traveling at 110km/h. Your argument diverts your attention from the police car for 2.0s (long enough for you to look at the phone and yell, "I won't do that!"). At the beginning of that 2.0s, the police officer begins braking suddenly at 5.0m/s^2. (a) What is the separation between the two cars when your attention finally returns? Suppose that you take another 0.40s to realize your danger and begin braking. (b) If you too brake at 5.0m/s^2, what is your speed when you hit the police car?

Homework Equations

Sorry! I have no idea which equations do I have to apply to...

The Attempt at a Solution

Sorry! please help me to find solution...

 

[learningphysics]

In these type of problems, you want an equation that gives you position (ie displacement) in terms of time... so look for those types of kinematics equations...

Also, you need to decide when your t=0 time is... when is it convenient to set t=0... for this case I think the best time is right when the two cars are separated by 25m and the police car begins braking...

So at t = 0, your car is at x =0 and the police car is at x = 25... try to find an equation for the position of your car in terms of time...

Try to find an equation for the police car also...