A)What is the separation between the two cars when your attention returns? B)Sup

Question

A)What is the separation between the two cars when your attention returns? B)Suppose you take another .400 seconds to realize your danger and begin breaking. If you too break at 5m/s^2 what is your speed when you hit the police car? My Not You are arguing over a cell phone while trailing an unmarked police car by 33.0 m. Both your car and the police car are traveling at 100 kmh, Your argument diverts your attention from the police car for 2.10 s (long enough for you to look at the phone and yell, /I won't do thatr"). At the beginning of that 2. 10 s, the police officer begins emergency braking at 5.00 m/'s? (a) What is the separation between the two cars when your attention finaly returns? 25.61 (tb) Suppose that you take another 0,400 s to realize your danger and begin braking, If you too brake at 5.00 m/s?, what is your sosed when you hit the polde km/h Constant-acceleration equations. During the lack of attention, how far does your car move and how far doen the (slowing) police car move? During the realization period, how far do you move and how far does the police car move? What is the police car's speed then? Set up two simultianeous equations for the rest of the motion: one for how far you travel and one for how far the police car travels. When do you and the police car have the name coordinate? Additional Materials Section 24 Algobra-Squareroots&Squares

Explanation / Answer

a] initial speed = 100 km/h = 100*5/18 m/s = 27.78 m/s

separation = 33 + distance travelled by police car - distance travelled by my car

= 33 + (ut +0.5at^2) - ut

= 33 + [27.78*2.10 - 0.5*5*2.10^2] - 27.78*2.10

= 21.975 m answer

b] separation just before applying brakes = 33 + [27.78*2.5 - 0.5*5*2.5^2] - 27.78*2.50 = 17.375m

police car velocity at this time = u +at = 27.78 - 2.5*5 = 15.28 m/s

time taken after applying brakes to hit the car:

separation = 0 = 17.375 + [15.28*t - 0.5*5*t^2] - [ 27.78*t - 0.5*5*t^2]

12.5t = 17.375

t = 17.375/12.5 = 1.39 s

velocity when it hits the car v = u - at = 27.78 - 1.39*5 = 20.83 m/s = 75 km/h answer

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